List of the most common diseases from smoking. Cancer and smoking Dependence of oncological diseases on maternal smoking
Cancer is the second leading cause of death after cardiovascular diseases. Lung tumor among oncology occupies a leading position in terms of frequency of occurrence, especially in men. Statistics are stubborn things. Men smoke more than women (so far, anyway), and lung cancer is more common in men, I think the relationship is pretty clear: smoking leads to cancer. But first things first.
Smoking is a very common bad habit. In 90% of cases, smoking causes nicotine addiction That is why tobacco is called a household drug. Every year, up to 5 million people die from the effects of smoking worldwide. After all, smoking causes cancer. Only weapons of mass destruction can compare with this. The problem of smoking is global. Only through the participation of all countries in tobacco control can we expect any serious results.
The money that smokers spend on cigarettes fills the wallets of tobacco workers and supports the economies of already developed countries. But the health problems of smokers in lagging countries are forced to solve local health care and only at their own expense.
According to the World Health Organization, every third person on earth is a smoker. In our country every year the number of smokers is only increasing. Currently, approximately 65% of men and 15% of women in Russia smoke. There are a lot of teenagers who smoke.
The fact that tobacco smoke is carcinogenic (which means it can cause a tumor) has long been proven. The smoke contains a lot of substances (more than 3500). When smoking, as a rule, all of them do not burn out. Most carcinogens are found in resins. These include, for example:
aromatic amines;
nitrosamines;
polonium;
polycyclic aromatic hydrocarbons (PAH).
Lung cancer is the most common type of cancer caused by smoking. It develops from the bronchial epithelium. Depending on the primary localization, it is divided into:
central;
peripheral;
mixed.
There are several types of lung tumors:
squamous;
small cell;
large cell;
mixed.
In general, the prognosis of this disease is unfavorable. Mortality is very high, up to 80%. Most often, people cannot live even five years.
Lip cancer
Cancer of the lip develops from the cells of the epithelium of the red border of the lips and is defined as a protruding seal with ulcerations and cracks in the skin. Of all types of tumors, it ranks 8-9th. The cancer of the lower lip is more common than the upper lip. Men get sick more often.
The most likely lip cancer from smoking in the presence of any damage to the mucous membrane of the inner border of the lips. This accelerates the entry of carcinogenic substances of tobacco smoke into the cells of the mucosa. Mutations in the cells of this layer can lead to the onset of their uncontrolled division and tumor development.
A favorable prognosis for lip cancer directly depends on how soon adequate treatment is started. The appearance of the following complaints will help a smoker to suspect this disease:
hypersalation (increased salivation);
discomfort or itching while eating;
dryness and peeling of the red border of the lips.
tracheal cancer
This type of tumor is quite rare compared to lung cancer and lip cancer. It develops from the epithelial cells of the trachea. Smoking leads to cancer and usually causes squamous cell carcinoma of the trachea. In the early stages, it is also asymptomatic. But you can pay attention to the following harbingers:
dry, irritating cough;
unexplained anemia;
frequent upper respiratory tract infections;
persistent subfebrile fever (up to 38.0⁰ WITH).
Mammary cancer
To date, there is no reliable evidence of a direct relationship between smoking and breast cancer. And cigarette smoke does not directly come into contact with these organs. But statistically, in women who smoke, this pathology occurs for some reason more often. First of all, this is due to the fact that smoking leads to cancer, including breast cancer.
One of the first signs of this disease is the appearance of seals in the mammary gland. When such signs appear, you need to consult a mammologist or at least a surgeon. After the age of 40, women should definitely do a mammogram once a year for the early detection of breast cancer.
Smoking and cervical cancer
Women who smoke and carry the human papillomavirus type 16 (HPV-16) have a higher risk of cervical cancer than those with only one of these two factors.HPV-16 infected female smokers were 14.4 times more likely to develop cervical cancer than HPV-negative female smokers. In nonsmoking patients, positive HPV-16 was associated with a 5.6-fold increased risk of cancer.
Smoking, together with high levels of HPV-16, increased the risk of cervical cancer by 27 times compared to HPV-negative women smokers. In nonsmoking patients, the increased risk associated with high levels of HPV-16 was only 5.9-fold.
There was a significant correlation between the duration of smoking and the presence of HPV-16, the researchers state.
The results of this study imply a synergism between HPV and smoking that significantly increases the likelihood of developing cervical cancer in HPV-positive female smokers, which places such patients at risk, requiring careful monitoring.
Smoking and prostate cancer (prostate cancer)
Modern long-term studies and observations of medical scientists prove that men aged 40-65 years old with a smoking experience of 20-40 years have a chance of getting sick prostate cancer twice as many as men who have never been heavy smokers. Smoking men of this age who suffer from prostate adenoma have a chance of getting sick prostate cancer many times more.
The influence of smoking on the creation of favorable conditions in the body of a man for the occurrence of prostate cancer has several directions:
However, there are also pleasant facts based on long-term observations of scientists: if a former heavy smoker with a long smoking history does not smoke for 10 or more years, then the risk of developing prostate cancer in such a person is equal to the risk of a person who has never smoked. So it's better to quit smoking.
Cancer of the digestive and urinary systems
Esophageal cancer, pancreatic cancer, bladder cancer, and kidney cancer are also not directly related to smoking. However, they are more common in smokers for the same reasons as breast cancer in women who smoke. The mucous membranes of these organs are able to accumulate in themselves the toxins contained in cigarettes and getting into it with smoking.
Signs of a cancerous lesion in the digestive and genitourinary systems depend on the stage and location of the tumor lesion. Unfortunately, the initial stage they have the same asymptomatic.
It is important to understand that smoking is a predisposing factor for the occurrence of any type of tumor. With a high probability, smoking leads to cancer of those organs with which cigarette smoke is in direct contact (lungs, trachea, bronchi, oral cavity). The lethality of these lesions is high, patients often do not live even 5-7 years. In this regard, there can be no doubt about the dangers of smoking for humans.
How to quit smoking without gaining weight?
Why do people gain weight when they quit smoking? This happens for the following reasons:
Sharpening of the sense of smell.
Replacing the “smoking” of stress with its “jamming”.
Decreased production of adrenaline.
Normalization of glucose uptake.
Be sure to drink a course of vitamins, especially important for such a period - this is to compensate for the lack of ascorbic acid and group B.
Do not keep candy or seeds on hand. Abuse of these products can lead to rapid weight gain.
It is necessary to start exercising, this will help get rid of calories and add endorphins to the blood, but at the same time increase the pace gradually, since the combination of stress that the body experiences at first from a lack of nicotine with stress during increased sports can lead to unpleasant consequences.
Some people who quit smoking may develop swelling. This is due to the effect of nicotine on the accelerated excretion of fluid. Such a phenomenon can be misinterpreted and mistaken for weight gain. However, after some time, the function of the kidneys is restored, and the swelling disappears.
Weight should be monitored especially carefully in the first two years after completely quitting smoking. It is believed that after this, the metabolism returns to normal, and the body completely gets rid of nicotine dependencies .
Excess weight, of course, is harmful and unattractive. But a pack of cigarettes smoked in a day causes a stronger blow to the human body. In addition, a pale yellow complexion, plaque on the teeth and bad breath and clothes, combined with constant shortness of breath and coughing, are also few people will like. Therefore, you should gather all your willpower and stop smoking forever!
In the summer of 1957, Ronald A. Fisher, one of the founders of modern statistical science, sat down to write a lengthy letter in defense of tobacco.
The letter was addressed to the British Medical Journal, which a few weeks earlier had taken an anti-tobacco stance that cigarettes cause lung cancer. The editorial board considered that the period of data accumulation and analysis has come to an end. Now, its members wrote, "all modern means of publicity" must be used to inform the general public about the dangers of tobacco use.
In Fischer's opinion, it was all just panic hype, not backed up statistically. He was sure that it was not "harmless and soothing cigarettes" that posed a danger to the masses, "but the organized cultivation of a state of wild anxiety."
Fischer was known as a hot-tempered man (and a heavy pipe smoker), but the letter and the controversy that arose from it, which continued until his death in 1962, were seriously criticized by the scientific community.
Ronald E. Fisher devoted much of his career to developing ways of mathematically evaluating claims of causation, just like the British Medical Journal did about smoking and cancer. And in his professional career, he has managed to revolutionize the methods used by biologists in experiments and in data analysis.
We all know how this controversy ended. On one of the most significant public health issues of the 20th century, Fisher was proven wrong.
But while Fischer was wrong about certain details, it cannot be said that he was wrong about the statistics. Fisher denied not the possibility that smoking causes cancer, but only the certainty with which public health advocates proclaimed this conclusion.
“No one thinks that it is possible to draw final results on this topic,” he insisted in his letter. “Isn’t she serious enough to require serious treatment?”
The debate about the dangers of smoking is over these days. However, on some issues, from public health, education, the economy, to climate change, researchers and decision makers still don't always agree on what can be called a truly "serious attitude."
How can anyone say with certainty that A causes B? How can one assess the consequences of intervention too early versus too late? And at what point can we put aside painful doubts, stop arguing and start taking action?
Great ideas and hostility
Ronald Fisher was known not only for his amazing intellect, but also for his surprisingly difficult temper. Two qualities, between which, oddly enough, you can find a connection.
Writer and mathematician David Salzburg, who described the history of 20th-century statistics in his book The Lady Tasting Tea, says that Fisher was often frustrated by those who could not see the world in the same way is he.
And only a few could.
Already at the age of seven, Fisher, a sickly myopic boy who did not have many friends, began attending lectures on academic astronomy. As a student at Cambridge, he published his first scientific work, where he introduced a new technique for identifying unknown characteristics of the population. The concept, dubbed "Maximum Likelihood Estimation", was later hailed as "one of the most important advances in statistical science of the 20th century."
A few years later, he began to investigate the statistical problem that Karl Pearson, then one of the most respected statisticians in England, had been trying to solve for several decades. The question was about the difficulty for a scientist with a limited set of data to calculate how different variables (such as rainfall and crop yields) relate to each other. Pearson's research focused on how such calculations might differ from the actual correlation, but because very complex mathematical calculations were involved, he dealt with only a small number of examples. After working for one week, Fisher solved the problem for all the examples. Pearson initially refused to publish the article in his statistical journal, Biometrics, because he himself did not fully understand the solution.
“The implications were so obvious to Fischer that he found it hard to make them understandable to others,” writes Salzburg. “Other mathematicians spent months and even years trying to prove something that Fischer took for granted.”
Not surprisingly, Fischer was not particularly popular with his colleagues.
Although Pearson eventually agreed to publish Fisher's work, he published it as supplementary material to a much longer work of his own. Thus began a disagreement between these two personalities, ending only with the death of Pearson. When his son, Egan, also became a well-known statistician, the Fisher-Pearson confrontation continued.
As one witness noted, Fischer had "a remarkable talent for controversy," and his professional disagreements often spilled over into personal animosities. When Polish mathematician Jerzy Neyman presented his research to the Royal Statistical Society, Fischer opened the post-lecture discussion with a mockery of the scientist. Fisher, in his words, hoped that Neumann would speak on "a topic that the author is well acquainted with and on which he could express an authoritative opinion," but his (Fischer's) hopes were not destined to come true ...
Although, as Salzburg reports, Fischer's irritable temper "practically drove him out of the mainstream of mathematical and statistical research," he nonetheless contributed to these disciplines.
After the failure of Pearson Sr., Fisher accepted a position in 1919 at the Rothamsted Agricultural Experiment Station in north London. It was here that he introduced his principle of randomization (Randomization) as one of the most important tools for scientific experiments.
At that time, the research station was studying the effectiveness of fertilizers by applying various chemicals to different areas of the earth. Field A received fertilizer 1, field B received fertilizer 2, and so on.
But Fisher said that such a path is doomed to produce meaningless results. If the crops of field A grow better than field B, the question arises: did this happen because fertilizer 1 was better than fertilizer 2, or because field A had more fertile soil?
The fertilizer effect was distorted by the field effect. The distortion made it impossible to pinpoint exactly what caused what.
To solve the problem, Fischer suggested applying different fertilizers to small areas in random order. Then, even though Fertilizer 1 will occasionally be applied to a fatter plot than Fertilizer 2, both will be randomly applied to enough plots for the reverse to happen just as often. In general, these differences are leveled. On average, the soil with the first fertilizer should look exactly like the soil with the second.
It was a big discovery. By randomizing the experimental exposure, the researcher could more confidently conclude that it was Fertilizer 1, rather than some confounding variable like soil quality, that caused better crop growth.
But even if the researcher used randomization and found that different fertilizers led to different yields, how could he know that these differences were not due to random variations? Fisher came up with a statistical answer to this question. He called the method "analysis of variance", in English "analysis of variance" or briefly ANOVA. According to Salzburg, this is "perhaps the single most important tool in biological science."
Fisher published his findings on research technique in a series of books from the 1920s and 1930s, and they had a profound effect on scientific inquiry. Researchers in every field — agriculture, biology, medicine — suddenly have a mathematically rigorous way of answering one of the main questions of science: what causes what.
Arguments against smoking
Around the same time, British health officials were concerned about one casual issue in particular.
While most of the diseases that had killed Britons for centuries faded away, thanks to advances in medicine and improved sanitation, one disease continued to kill more and more people each year: lung carcinoma.
The numbers were staggering. Between 1922 and 1947, lung cancer deaths increased 15-fold in England and Wales. Similar trends have been observed around the world. Men were the main victims of the disease everywhere.
What was the reason? There were many theories. More people than ever before lived in large polluted cities. Cars belching toxic fumes filled the national highways. The roads themselves were covered with tar. X-ray technologies developed, with the help of which more accurate diagnoses could be made. And, of course, more and more people began to smoke cigarettes.
Which of these factors had the most influence? All? None of them? English society had undergone such significant changes in many areas of life since the First World War that it was simply impossible to pinpoint a single cause. As Fisher would say, there were too many confounding variables.
In 1947, the British Medical Research Council hired Austin Bradford Hill and Richard Doll to look into the matter.
While Doll was not widely known at the time, Hill was the obvious choice. A few years earlier, he had gained popularity with the release of his groundbreaking research on the use of antibiotics to treat tuberculosis. Just as Fisher randomly distributed fertilizer to the fields in Rothamsted, Hill also randomly gave streptomycin to some patients while prescribing bed rest to others. Here the goal was the same—to make sure that patients who received one type of care were, on average, identical to those who received another. Any significant difference in outcome between the two groups must have been the result of drug use. This was the first published medical trial to use a randomized control.
Despite Hill's seminal work using randomization, the question of whether smoking (or anything else) causes cancer has not yet been subjected to Randomized Control Trials. In any case, such an experiment would be considered unethical.
“This would require the participation of a group of, say, 6,000 people, of which 3,000 would be selected and forced to smoke for 5 years, while the rest would be banned from smoking for the same 5 years. Then they would compare the incidence of lung cancer in these two groups, says Donald Gillies, emeritus professor of philosophy of science and mathematics at University College London. “Naturally, this is impossible to implement, so in this example, you have to rely on other types of supporting data.”
Hill and Doll tried to find such evidence in London hospitals. They tracked the medical records of more than 1,400 patients, half of whom suffered from lung cancer and the other half were hospitalized for other reasons. Then they, as Doll would later say in an interview with the BBC, "asked them every question we could think of."
The questions included medical history and family history, work, hobbies, place of residence, eating habits, and other factors hypothesized to be associated with cancer. Two epidemiologists acted at random. It was hoped that one of the many questions would touch on some characteristic or behavior that was common among those with lung cancer and rare in the second control group.
At the beginning of the study, Doll had his own theory.
“Personally, I thought that the reason lay in the tar road surface,” reported Doll. But as the first results emerged, various recurring scenarios began to emerge: “And I quit smoking after two-thirds of the research journey.”
Hill and Doll published their findings in the British Medical Journal in September 1950. The discoveries caused certain concerns, but were not final. Even though smokers were more at risk of the disease and that the incidence increased with more cigarettes smoked, the nature of the study still left room for Fisher's daunting "distortion" problem to operate.
It consisted in the choice of control groups. Hill and Doll selected comparative groups of people of the same age, gender, location (approximately), and social class. But did this cover the entire list of possible causes of distortion? Was there some feature, forgotten or invisible, that the two scientists hadn't thought to inquire about?
To get to the bottom of the truth, Hill and Doll designed a study in which they would not have to choose control groups at all. Instead, they interviewed over 30,000 doctors across England. They were asked questions about smoking habits and medical history. And then Hill and Doll began to wait... who would die first.
By 1954, familiar scenarios began to emerge. Among all British doctors, 36 have died of lung cancer. All of them were smokers. Again, the death rate increased with the volume of cigarettes smoked.
The British Doctor Study had a clear advantage over the previous patient survey. Scientists could now clearly show the first-it-then-that relationship (or, as medical researchers call it, dose-response). Some doctors smoked more than others in 1951. By 1954 most of them were dead.
The successive studies by Doll and Hill were popular for their quantitative coverage, but not only did they find a consistent relationship between smoking and lung cancer. Around the same time, American epidemiologists I.K. Hammond and Daniel Horn (E. C. Hammond, Daniel Horn) conducted a study very similar to a survey of British doctors.
Their results have been very, very consistent. In 1957, the Medical Research Council and the British Medical Journal jointly decided that enough information had been collected. Quoting Doll and Hill, the magazine declared that "the most reasonable interpretation of this evidence would be to accept a direct causal relationship."
Ronald Fisher allowed himself to disagree.
I'm just asking questions
In some ways, the timing was right. In 1957, Fischer had just retired and was looking for a place where he could apply his extraordinary mind and arrogance.
Fisher fired the first volleys of guns, calling into question the certainty with which the British Medical Journal declared the end of the controversy.
“This is a good example of having enough strong evidence to continue the investigation,” he wrote. “However, the subsequent investigation seems to have been reduced to making even more confident exclamations.”
The first letter was followed by a second, and then a third. In 1959, Fischer compiled all the messages into a book. He accused colleagues of creating anti-smoking "propaganda". He blamed Hill and Doll for suppressing facts that contradicted the official statement. He began to lead a course of lectures, again having the opportunity to orate to the color of statistical science and be, in the words of his daughter, "deliberately provocative."
All provocations aside, it is worth noting that Fisher's critique came to the same statistical problem that he wrestled with in his time at Rothamsted: confounding variables. He did not challenge the claim that there is a relationship, or correlation, between smoking frequency and lung cancer incidence. But in a letter to Nature, he chided Hill and Doll, and with them the rest of the British medical community, for committing “the old reasoning error of inferring causation from correlation.”
Most researchers have looked at the relationship between smoking and cancer and have concluded that the latter is caused by the former. But what if the opposite is true? What if, he wrote, the development of the acute stage of lung cancer was preceded by "chronic inflammation"? And what if this inflammation led to a feeling of discomfort, but not conscious pain? If that was the case, Fischer continued, it makes sense that early, undiagnosed cancer patients were turning to cigarettes in search of symptomatic relief.
Therefore, regarding the initiative of the British Medical Journal to ban smoking in cinemas, he wrote the following: “Taking away the cigarettes from the poor fellow is tantamount to someone taking the wand from a blind person.”
The sedative properties of cigarettes were often mentioned in mid-20th century tobacco advertisements. This ad is from 1930: "20,679 therapists claim 'Luckies are less irritating'." They relax. Protecting your throat, against irritation, against coughing"
If this explanation still seems far-fetched, then we can turn to another one proposed by Fisher: if smoking does not cause cancer, and cancer does not cause smoking, then perhaps there is a third factor that causes both. Genetics gave him the opportunity to support this conclusion.
Fischer collected material on identical twins in Germany and demonstrated that twin sisters/brothers tended to copy their couple's smoking habits. Probably, Fischer reasoned, some people were more genetically predisposed to desire to smoke.
Was there a similar family pattern for lung cancer? Did not these two predispositions come from the same hereditary trait? At the very least, pundits could look to that possibility before advising people to quit cigarettes. But then no one bothered to do it.
“Unfortunately, there is already a lot of propaganda going on to convince the public that cigarette smoking is dangerous,” Fischer wrote. “It seems natural for someone to make an effort to discredit evidence that advocates a different point of view.”
Although Fisher was in the minority, he was not alone in his commitment to a "different point of view." Joseph Berkson, chief statistician at the Mayo Clinic in the 1940s and 50s, was a confirmed skeptic on this issue, as was Charles Cameron, president of the Americas. -lo-gi-chess-whom society. For some time, many of Fisher's colleagues in academic statistical circles, including Jerzy Neumann, questioned the validity of the British medical claims. But, some time later, almost everyone gave in under the weight of mounting evidence and majority consensus. But not Fischer. He died in 1962 (of cancer, though not of the lungs), without losing one iota.
Hidden motives
Today, not everyone takes Fisher's views on the tobacco problem at face value.
In his review of the controversy, epidemiologist Paul Stolley sharply criticized Fisher for "unwillingness to seriously consider the available data, pay attention to the facts and try to come to the right conclusions." According to Stolley, Fischer compromised Hill's and Doll's reasoning by looking for breaking discoveries and exaggerating them. His use of material on the German twins was either erroneous or deliberately misleading. He writes that Fischer "gives the impression of a man with some sort of personal interest."
Others give much less condescending interpretations of history.
In 1958, Fisher approached the British hematologist and geneticist Arthur Mourant, proposing a collaborative project to assess possible genetic differences between smokers and non-smokers. Muran turned him down and then repeatedly shared his opinion that the "obsession" of the statistician with this topic "was the first sign of the decline of a once so incomparably brilliant mind."
Even worse are the suggestions that his skepticism came at a cost. The Tobacco Manufacturers' Committee allegedly agreed to fund Fisher's research on the possibility of a genetic predisposition to smoking and lung cancer. And while it seems incredible that a man who was not afraid to offend colleagues and regularly jeopardized his career just to prove himself right, would sell his professional opinion at such an advanced age, some still believe that this is exactly what happened.
Even if Fischer was not attracted to money, his exposure to political influence may be plausible. Fischer was a staunch reactionary all his life. In 1911, while studying at Cambridge, he participated in the founding of the University Society of Eugenicists. Many educated people in England of that era adhered to this ideology, but Fisher took up the study of the topic with extraordinary zeal and later throughout his career wrote articles about it periodically. Fisher was especially concerned that families at the top of society had fewer children than members of the poorer and less educated social classes. He once even suggested the idea that the government should pay a special allowance to "intelligent" couples to continue their offspring. Fischer himself and his wife had eight children.
These and similar political leanings may have colored his perception of the problem of smoking.
“Fischer was a political conservative and an elitist,” notes Paul Stolley. "He was frustrated by the response of public health officials to the dangers of smoking, not only because he felt there was little supporting evidence, but also because of his ideologically driven rejection of mass public health campaigns."
If Ronald Fisher were alive these days, he would have that Twitter profile...
When does correlation indicate causation?
Whatever Fischer's motives, it's hard to be surprised that he allowed himself to be dragged into this fight. He was a man who built a career thanks to a thorough approach to scientific work. This allowed him to avoid the pitfalls of distortion and to point out with mathematical precision where correlation suggested causation and where it did not.
The fact that a younger generation of health professionals (as well as members of the press) had come to such an important conclusion without following Fisher's own rules of causality must have infuriated him. Fisher himself admitted that it would be impossible to conduct a randomized trial with smoking control groups. “It’s not Hill’s or Doll’s or Hammond’s fault that they can’t provide evidence for an experiment in which a thousand teenagers would be banned from smoking,” Fisher wrote, “but at the same time a thousand other children would be forced to smoke at least thirty cigarettes a day. day". But in a situation where scientists have to deviate from the gold standard of conducting experimental study, he insisted, they need to give credit to every explanation.
This debate could go on for eternity to some extent.
“Almost everyone these days admits that Fisher was wrong, but there are still modern difficulties of this kind, creating numerous prerequisites for challenging certain things,” says Donald Gillis of University College London. - What causes obesity? What dietary habits, if any, lead to cardiovascular disease and diabetes?
Add to this the never-ending debate on education (does higher school budgeting improve the quality of education?), climate change (is rising air pollution causing global warming?), crime, and punishment systems (do higher penalties lead to reduce crime?) and less complex everyday life (is flossing good for teeth? does coffee cause cancer? or prevents it?).
Correlation does not always indicate conditionality: the author of this table shows a correlation between the winning words in the national competition for the correct pronunciation and the number of people who died from the bite of poisonous spiders. Obviously, this is just a coincidence. With so many things going on in the world, it's easy to select some unrelated phenomena to compare and find similar trends.
While experiments with random assignment of objects to control groups are seen as the gold standard for separating simple correlation and causation, common sense and ethics often tell us that we should make do with what we have, notes Dennis Cook, professor of statistics. at the University of Minnesota. We are subjective. “But there needs to be a balance,” he adds.
Cook recalls a popular headline study a few years ago that found a statistically significant association between cranberry consumption and cancer. Should society impose a ban on this berry?
“The point of Fischer's view is that you can't make decisions based on a reflex response,” says Cook. - Some decisions based on a reflex reaction will be correct, as happened with smoking. But others, like the cranberry example, would be fundamentally wrong.”
One of Ronald Fisher's most important contributions to modern statistics is the concept of the Null Hypothesis. This is the starting point of any statistical test - the assumption that, in the absence of evidence to the contrary, you should not change your mind. When in doubt, assume the fertilizer didn't work, the antibiotic didn't work, and smoking doesn't cause cancer. The unwillingness to “reject zero” gives rise to an internal conservatism in science that keeps existing knowledge from going wild in circles with each new cranberry research.
But even this approach can lead to falling on shaky ground.
In 1965, three years after Fisher's death, Austin Bradford Hill, by then a professor emeritus and knighted, gave a speech to the Royal Society of Medicine. In it, he outlined a number of criteria for reflection before declaring that one thing is the cause of another. But most importantly, he said, none of these criteria should be considered immutable. "Once and for all" established rules of statistics do not completely eliminate uncertainty. They only help informed people with worthy intentions choose the best possible solutions.
“Any scientific work is incomplete,” he said. — Any scientific work is open to refutation or correction by knowledge of a higher level. This does not give us the freedom to ignore what we already know, or to delay the action required at a given moment in time.”
Ronald Fisher invented an ingenious way to separate correlation and cause. But obtaining absolute proof comes at a high cost.
The fact that the passion for cigarettes has an extremely negative effect on human health is well known to all modern people. But most ordinary smokers still have very little information about what kind of poisonous mix they actively inhale almost every hour. And speaking about what specific substances in tobacco smoke lead to the development of diseases, most cigarette addicts will only remember nicotine and tar.
In fact, when a cigarette smolders, several thousand toxic substances enter the surrounding air, about 70 of them are extremely dangerous carcinogens. One of the most unfortunate consequences of smoking doctors include oncology. The formation of cancerous tumors in smokers causes a number of mutagens that are part of tobacco smoke. Doctors have found that smoking provokes the development of about 17 types of cancer. This fact is worth discussing in more detail.
Smoking in almost 90% leads to the development of oncological processes
When a cigarette smolders, a huge amount of chemicals are actively released.. Some of them are quite safe for humans, but there are a number of formations that are deadly.
It has been established that if you smoke a pack of cigarettes every day for a year, then a number of irreversible processes begin in the human body - the cells of the larynx and lungs begin to mutate.
To understand why smoking causes cancer, it is worth learning more about the composition of tobacco smoke. The table below lists the most dangerous toxic elements that are responsible for irreversible mutagenic processes.
| Name | Description | Harm |
| nicotine | main ingredient in any cigarette | increases blood pressure, blocks the transmission of nerve impulses, promotes vasoconstriction, causing strokes and heart attacks |
| resin | solid particles deposited in the lungs and trachea | provokes various problems in the work of the respiratory system, becomes the culprit of cancer, COPD, bronchitis and pneumonia |
| cadmium, lead and nickel | heavy metals contained in every cigarette | dangerous diseases of the respiratory system, carcinogenic elements leading to irreversible processes in cellular tissue |
| benzene | hydrocarbon, solvent used in the chemical industry | a powerful carcinogen that leads to cell mutation, the culprit of the appearance of oncological processes, it has been established that it is benzene that provokes the development of leukemia in smokers |
| formaldehyde | poisonous compound | causes problems in the functioning of the digestive tract and respiratory systems |
| carbon monoxide | toxic substance produced when a cigarette burns | actively connects with blood cells and prevents the enrichment of internal systems with oxygen |
| styrene | used to make polystyrene | poisonous compound of the III level of danger, leads to catarrh of the lungs, changes the composition of the blood and causes inflammation of the mucous membranes |
According to the latest estimates, it has been established that each cigarette, when it is smoked, produces about 4,000 harmful substances in the surrounding air. Of these, 400 are toxic and 43 belong to the class of carcinogens.. The following compounds are considered to be compounds that directly cause oncological processes:
- chromium;
- nickel;
- lead;
- cadmium;
- benzene;
- arsenic;
- saltpeter;
- nicotine;
- benzopyrene;
- vinyl chloride;
- formaldehyde;
- 2-naphthylamine;
- aminobiphenyl;
- hydrocyanic acid;
- N-nitrosopyrrolidine;
- N-nitrosodiethanolamine;
- N-NITROSODIETHYLAMINE.
How cancer develops in smokers
The human lungs are made up of many tiny sacs (alveoli). These formations are covered with a special fabric, the work of which is to block the entry of bacteria and harmful compounds and their timely evacuation from the body. The constant intake of carcinogens and tobacco smoke compounds into the lungs leads to the death of the protective layer of the epithelium.
Provokes cancer carcinogens, which are found in large quantities in tobacco smoke
All harmful substances begin to gradually deposit on the walls of the lungs and enter the bloodstream. As soon as the concentration of toxic components and carcinogens in the blood exceeds the maximum allowable rate, oncological processes begin to develop in the smoker's body. When exactly a smoker will cross the fatal line, it is difficult to say - a lot depends on the physiological characteristics of a person.
Carcinogens - the culprits of oncology
Carcinogenic substances tend to accumulate in the human body. They can be called a "ticking mechanism bomb". It is noted that they are most actively stored in such organs as:
- liver;
- intestines;
- epidermis;
- thyroid;
- respiratory system.
Doctors distinguish a separate risk group, people who are friends with cigarettes and have the most frequent chance to get acquainted with oncology. These are the following points:
- Bad, poor quality food.
- Work in a hazardous industry.
- Living in areas with unfavorable ecology.
- Undertreated inflammatory processes in the body that have passed into the chronic stage.
The most common diseases
Carcinogens can become the culprit of the cancerous process in almost any organ. Accumulating in the body for years, they actively destroy cell chromosomes, which leads to a change in the DNA structure and the appearance of cell mutations. As a result, the cell becomes cancerous. According to medical statistics, the most common cancers among long-term cigarette addicts are:
- Lip cancer. Included in the top ten most common oncological processes, occurs in 7-8% of all cases of diseases of this kind.
- Lung cancer from smoking, statistics speak of him as a leader in oncology. It accounts for about 56–60% of cases of oncological processes.
- Cancer of the trachea (throat). Most often it occurs in male smokers and occupies 35–40% of all recorded cases.
- Stomach cancer. According to medical statistics, about 10% of men and 12% of women among other cancer patients die from this pathology every year.
Oncology of the lip (squamous cell carcinoma)
This is one of the most dangerous and serious manifestations of oncological processes. It most often develops on the lower part of the lips and has the appearance of a seal protruding beyond the edges of the red edging, covered with cracks and sores. Lip cancer develops especially quickly from smoking not in puffs. Among smokers, doctors note the greatest predisposition to this type of oncology in the following situations:
- heredity;
- temperature burns;
- frequent injury to the mucous membrane;
- infectious diseases of the oral cavity.
Lip cancer is a common form of cancer in smokers.
The development of the oncological process on the lips takes quite a long time. But the disease can be dealt with, subject to timely diagnosis, smoking cessation and competent therapy. Symptoms that should alert a cigarette addict and serve as a reason for a visit to the doctor are as follows:
- burning and itching;
- increased salivation;
- unpleasant, painful sensations when eating;
- the appearance of long-term non-healing cracks and sores;
- the formation of roughness in the affected area;
- soreness in the region of the mucosa of the lips and the upper border.
Lung cancer (adenocarcinoma)
A malignant formation of this type is based on the development of tumors on the mucous membrane of the bronchi or lungs. The main culprit of the cancerous process is long-term smoking.
According to statistics, addiction to cigarettes for a long time in 80% of cases leads to the appearance of oncological processes in the lungs.
The chance to get acquainted closely with this deadly disease is directly proportional to the number of cigarettes consumed per day and the total smoking experience. It has been established that when smoking from one cigarette pack per day, the risk of developing adenocarcinoma increases by 30–60%. Moreover, even after a complete cessation of smoking, these figures will decrease only after 15–16 years.
Symptoms of lung cancer appear when the disease has already taken root in the body.
Lung cancer is notable for its insidiousness. A person may be unaware of the onset of oncology for a long time. You can suspect something is wrong by the following symptoms:
- complete loss of appetite;
- breathing difficulties;
- cough lasting more than a month;
- constant severe fatigue and weakness;
- separation of sputum with blood streaks;
- rapid weight loss (up to 6-7 kg per week);
- soreness when breathing, which increases when trying to cough.
These signs are the very first symptoms of the disease. There are a number of other symptoms that speak of adenocarcinoma, but they are not so common:
- hoarseness of voice;
- swelling of the neck and face;
- difficulty swallowing (even water);
- pain in the sternum, radiating to the hypochondrium.
Oncology of the trachea (squamous cell carcinoma)
This is a serious oncological disease that develops on the mucous tissue of the larynx and pharynx. Very often, cancers grow into nearby tissues and form secondary lesions.
According to statistics, men over the age of 40 who smoke most often get throat cancer, and those who abuse alcohol are at especially high risk of developing the disease.
Often, the occurrence of oncology is preceded by laryngitis, which often occurs and has already passed into the chronic stage (a constant companion of smokers). Adds a chance to face this disease and work in a hazardous industry, living in a bad environment. The severity of signs and the brightness of their manifestation depends on the location of the tumor.
Laryngeal cancer most commonly affects men
The most common symptoms of throat cancer are:
- hoarseness of voice;
- difficulty in swallowing;
- prolonged dry cough;
- bloody streaks when coughing and sneezing;
- unpleasant, putrid smell of the oral cavity;
- persistent sore throat (in the absence of a cold).
Oncology of the stomach (gastric adenocarcinoma)
Oncology of this type is characterized by a tendency to rapid progression and metastasis to other organs of the gastrointestinal tract. Cancer, germinating through the gastric walls, is deployed in the small intestine and pancreas. This process is accompanied by necrosis and subsequent internal bleeding. With the help of blood flow, cancer cells also metastasize to the liver, lungs, massively affecting the lymph nodes.
Stomach cancer can rapidly metastasize to nearby organs
Smoking and stomach cancer are true companions of each other. This type of cancer is one of the most common among active smokers. According to statistics, about 800,000 people die from gastric adenocarcinoma every year.
The insidiousness of pathology lies in its rapid and sometimes imperceptible development for the patient. Obvious symptoms are already felt during the process of II and III stages. At this stage, a person begins to be disturbed by such manifestations as:
- heaviness after eating;
- decreased appetite and rapid weight loss;
- nausea and vomiting immediately after eating;
- severe problems with the swallowing process;
- pain in the epigastric region (middle and upper abdomen, under the ribs).
This deadly process can be stopped and a complete cure can be achieved if the pathology is diagnosed in time and treated immediately. But, often the patient seeks help too late, joining the ranks of the sad statistics of cancer victims.
What conclusions do we have
Not only persistent and long-term smoking can bring a person to the appearance of deadly oncology processes. Cancer also occurs for a number of other reasons. But, evaluating and studying statistical indicators, among the favorites - the perpetrators of these processes, it is guaranteed that smoking can be put. This should be known and remembered always when the hand reaches out to open a cigarette pack.
Remember that each smoke break brings a person closer to the moment when the whole meaning of a smoker's life is the struggle for his own life and saving his health. And in order not to bring yourself to a fatal situation, you should make every attempt to forget about smoking forever.
In contact with
Lung cancer from smoking occurs when a person has a genetic predisposition to develop tumors. In addition to malignant processes, smoking can provoke and aggravate many other diseases of the respiratory system.
About 1 million cases of lung cancer are diagnosed every year in the world. In most patients, tumors are detected at stages 3-4 and are complicated by concomitant pathologies.
History of research on the association between smoking and cancer incidence
Even at the end of the 18th century, doctors noted that smoking causes health problems, in particular heart and lung diseases. But smoking in those days was not too widespread, mainly members of the elite smoked. Tumors in the lungs were very rare.
The incidence of respiratory tract tumors increased in the first half of the 20th century. This happened in connection with the invention of the machine that produces cigarettes and the widespread bad habit. For the first time, the relationship between smoking and lung cancer was established by L. Adler in 1912. Then S. Fletcher and his students published works in which, using mathematical calculations, he demonstrated changes in the life expectancy of a person depending on the length of smoking.
Modern scientists have found that tobacco smoke that penetrates the lungs with one puff contains 10 15 free radicals and 4700 chemical compounds. These particles are so small that they freely pass through the alveolar-capillary membrane, damaging the vessels of the lungs. They provoke inflammation and affect the DNA of dividing cells, resulting in cancer.
According to statistics, men get lung cancer 8-9 times more often than women. Smoking is recognized as one of the main factors provoking the growth of neoplasms. In addition to tobacco smoke, the causes of the development of the disease are air pollution and work in harmful conditions.
Mechanism of oncogenesis
- stimulate uncontrolled cell proliferation,
- interfere with the implementation of apoptosis - programmed cell death,
- cause disruption of the cell cycle
- block contact inhibition - the property of cells to inhibit division upon contact with each other.
The target cells that transform into cancer cells are Clara cells - epithelial cells devoid of cilia. Most Clara cells are found in the lower respiratory tract. Tumors that have developed as a result of tobacco smoking are most often poorly differentiated bronchopulmonary carcinomas.
Malignant tumors are characterized by invasive growth with damage to surrounding normal tissues. Benign tumors push away healthy tissues without damaging them. Neoplasms affect metabolism and cause multiple complications: pain, pulmonary hemorrhage, impaired respiratory function.
Tobacco smoke causes local inflammation. Tissue phagocytes migrate from the lumen of the vessels to the foci of inflammation. Increased levels of pro-inflammatory mediators. At the same time, the phagocytic activity of immune cells is reduced, making smokers more susceptible to respiratory infections.
Health effects of passive smoking
Lung cancer in non-smokers is caused by regular passive inhalation of tobacco smoke. But it is difficult to assess the difference between the effects of active and passive smoking on the body, due to the fact that the smoke exhaled by a smoker and the smoke emitted by a cigarette differ significantly in composition. In addition, smoke, spreading in the environment, changes its properties. However, passive smoking increases the likelihood of tumor formation and the development of other diseases of the respiratory system.
Other causes of lung cancer in non-smokers:
- genetic predisposition,
- exposure to industrial carcinogens,
- other types of cancer,
- human papillomavirus infection,
- exposure to radiation
- long-term residence in large industrial centers.
According to scientists, in 15-20% of cases, lung cancer is caused by air pollution from industrial enterprises and vehicle exhaust gases. A high frequency of the disease is noted among people working in difficult and harmful conditions. Among industrial substances that cause lung cancer, the most dangerous are: asbestos, mustard gas, beryllium, halogen ethers, arsenic and chromium compounds, polycyclic aromatic carbohydrates. Among agricultural workers, people who are constantly in contact with pesticides are at risk.
How much do you have to smoke to get lung cancer
In people who smoke for less than 10 years, the incidence of lung cancer increases slightly compared to non-smokers. But after 20 years of smoking, the figure increases by 10 times, after 30 years - by 20, after 45 years - by almost 100. The number of cigarettes smoked is of great importance.
According to the American Cancer Society, which followed up 200 thousand people for 7 years, it became known that the incidence of tumors is:
- non-smokers - 3.4 cases per 100 thousand people;
- those who smoke less than 1 pack of cigarettes per day - 51.4 per 100 thousand;
- those who smoke 1-2 packs of cigarettes per day - 143.9 per 100 thousand;
- heavy smokers who smoke more than 2 packs a day - 217.3 per 100 thousand smokers.
In addition to the number of cigarettes smoked, the appearance of neoplasms is influenced by the physiological and anatomical characteristics of a person, his age, lifestyle, environmental conditions and other factors.
The earlier a person starts smoking, the more likely they are to get lung cancer.. Even a small amount of cigarettes smoked in adolescence not only increases the likelihood of the disease, but also inhibits the development of the respiratory tract. In smoking adolescents, obstruction of small bronchioles and impaired function of external respiration are found. People who started smoking at the age of 15 are 5 times more likely to develop cancer than those who start smoking after 25. In girls, the consequences of early smoking are more pronounced than in boys.
In June 1957, the UK Medical Research Council issued a ruling titled "Smoking and Lung Cancer". It was the first official statement of this type to appear under the auspices of a government organization.
This set off a chain reaction, and other influential organizations began to make similar statements. For two years, this was announced by influential government organizations involved in healthcare in Denmark, Sweden, and the United States. In 1960, the World Health Organization joined them. And the Surgeon General of the United States put an end to this issue in 1964 by publishing a detailed report on this topic. Since his influence and authority were high, the medical community and society generally agreed that tobacco smoke causes lung cancer.
burden of proof
To us, the connection between cancer and smoking seems unshakable and eternal. It is hard to imagine that at one time this was not known. In fact, not everything is so simple. Before the advent of cigarettes, pipes were smoked, the smoke of which was not inhaled deeply, and the most common complication was cancer of the mouth and lips. With cigarettes, everything was also not so obvious, because before the development of lung cancer, you need to smoke for years. Doctors had suspicions about the carcinogenic effects of tobacco smoke, but there were no serious studies confirming this. One way or another, the first serious work showing the connection between cigarette smoking and lung cancer appeared only in May 1950. American scientists Ernst Winder and Evarts Graham published a study of over 600 lung cancer patients. Of these, 95.6% were heavy smokers who had smoked for twenty or more years. In their article, they conclude: “It seems that the less a person smokes, the less likely they are to develop lung cancer, and the more a person smokes, the more likely they are to develop this disease.”
In September of the same year, the second, larger and most famous study of English scientists appears. Richada Dolla and Bradford Hill, in which they explicitly state that there is "a real relationship between lung carcinoma and smoking". For the first time, they estimate the strength of the effect of smoking: those who smoke more than 25 cigarettes a day may have a 50-fold higher risk of lung cancer than those who do not smoke at all. Sir Doll went on to play a pivotal role in the war against the tobacco companies and became one of the most famous men in that battle, which continues to this day.
retaliatory strikes
After the publication of such studies, cigarette manufacturers became seriously worried and tried to turn the tide in their favor. In November 1952, the famous meeting of representatives of the Imperial Tobacco tobacco company with Dr. Green from the UK Medical Research Council, and with Doll and Hill. At the end of the meeting, Greene wrote that the scientists had answered all the cigarette manufacturers' questions in detail and left no hope that smoking did not cause cancer. But at the same time, the tobacconists did a good face on a bad game, refusing to believe it.
Over the next few years, more and more research appeared that cigarette smoking provokes the development of lung cancer. Plus, in an animal experiment (on humans, such studies were simply impossible) in Denmark, France, Japan and the United States, the carcinogenic effect of tobacco tar was demonstrated when applied to the skin. And in the UK and the US, this has been proven in experiments simulating smoking.Meetings between tobacconists, officials and scientists also continued, most of all they affected companies and people from the USA and Great Britain. This was understandable, because the largest tobacco companies came from these countries. At the same time, manufacturers spoke good words that, as soon as the link between cancer and smoking was unequivocally proven, they would take the most stringent measures against their business. But de facto they played their game, refused to recognize this connection. At the same time, tobacco companies began to develop joint tactics, organized PR campaigns, and then even decided to “invest” in research. They first offered the Medical Research Council covert funding for research into the effects of tobacco on health. But under such conditions, cooperation did not work out. Then they agreed to do it explicitly, creating a fund to finance research in 250 million pounds.
Who did win anyway?
De facto, in this way, the tobacco industry prolonged the refusal to recognize the connection between smoking and lung cancer and dragged out this process for several decades. So far, in the nineties, the mechanism of the carcinogenic action of benzapyrene was not specifically discovered and deciphered. The presence of this dangerous substance in tobacco smoke was already well known in the fifties. But to show how it all works at the level of molecules and genes, and how lung cancer develops, was able to show much later, when subtle methods of molecular biology appeared.
And in the fifties it was simply impossible. And then all the evidence was based on two sets of statistics: the very high prevalence of cancer among smokers and the very high number of smokers among lung cancer patients. Strictly speaking, such studies cannot speak of a causal relationship, that is, that smoking is the cause of cancer. Statistics speak only about the relationship between the two factors. But in relation to smoking and lung cancer, the relationship was so powerful, and, most importantly, dose-dependent (the more a person smoked, the higher the risk of cancer) that it was hard to imagine that tobacco smoke was not the cause of the disease.
By and large, tobacco companies managed to drag out the process of recognizing the carcinogenic effect of tobacco, and they began to pay large compensations to cancer patients by court decision only in the second half of the nineties. When a causal relationship was confirmed at the level of gene work. And when the first victims of tobacco, who learned about what caused their terrible disease, had already died without receiving any compensation.