Lung cancer is the most common cancer, which causes most deaths worldwide. To get an idea of the aggressiveness of this tumor, you should know that the mortality of lung cancer is higher than that of breast, prostate and bowel together.
Lung cancer is the second most common cancer in men, second only to prostate cancer, and the second most common cancer in women, behind breast cancer. However, lung cancer affects both men and women, unlike breast and prostate cancers, which arise in one sex only, it ends up being, in general, the most common of all cancers.
The accompanying graph shows the evolution of mortality from lung cancer in the U.S. over the past decades. In the following lines the jump in mortality since the 1940s will be explained. The data are American but may be applied to most countries.
The incidence of lung cancer is directly related to cigarette consumption by the population. Until the 20s of the 20th century, when the cigarette was still not produced and marketed on a large scale, lung cancer was a rare disease, accounting for less than 1% of all cancers.
In the early 20th century, only 0.5% of the U.S. population smoked more than 100 cigarettes (5 packs) per year. In the 1960s, the peak of smoking, 50% of the male population smoked at least 100 cigarettes (5 packs) per year. Knowing this information, go back to the graph and see the mortality curves.
Growth smokers
Since the 1980s anti-smoking restrictions have been increasingly implemented around the world to reduce the number of smokers. Thanks to them for the first time in decades, we noticed a reduction in mortality from lung cancer.
Just as a curiosity, the marketing campaign of the tobacco industry in the 1940s and 1950s was so strong and absurd suggesting that doctors and dentists recommended the use of certain cigarette brands. The major Hollywood stars and famous athletes sporting received thousands of dollars to promote cigarette brands. At that time being a smoker was a standard. Nonsmokers were a minority in many social circles. The result of all this efficient marketing campaign was a dizzying rise in the curve of mortality from lung cancer in the decades that followed.
As yet there are no tests that can detect lung cancer early enough to ensure healing with treatment, the best strategy is still prevention. To guard against any disease, it is essential to know their risk factors. So it is the risk factors of lung cancer that we talk about below.
Since the beginning of this text has made it clear, cigarette smoking is the main risk factor for lung cancer. 90% of patients who have lung cancer are or were smokers.
Unbelievably it is still possible to find people who are fooled by false reports about an alleged lack of evidence of the relationship between smoking and lung cancer. Since the 1960s it has no scientific evidence that smoking causes lung cancer. Currently we know, which genetic changes are caused by toxic cigarette responsible for the emergence of cancer cells.
What we know today about the relationship of smoking with lung cancer:
Those who smoke at least one pack of cigarettes per day are up to 25 times more likely to develop lung cancer compared with nonsmokers.
Over 4000 toxic substances in cigarettes have been identified and at least 50 that are known to cause cancer.
After 15 years of abstinence the risk of lung cancer drops by 90%. However, it will never be as low as that of those who never smoked.
There is a minimum number of cigarettes per day, which is safe or types of cigarettes that do not cause cancer. We know that if you smoked more than 100 cigarettes in your life, you are in a high risk group for developing lung cancer. Whether you smoke 1 cigarette per day or 1 week.
The higher is your daily consumption, the longer is the duration of smoking and the earlier you start smoking, the greater is the risk.
Passive smokers have 25% more risk of developing lung cancer than people not exposed chronically to cigarette smoke.
Cigar, pipe and marijuana
Cigar and pipe
There is a myth that only cigarette smoking is a risk factor for lung cancer. This supposed lack of damage is even stronger when we speak of marijuana, a drug, discussion of which is guided more by emotion than by scientific and statistical data. Chronic use of marijuana causes changes in the cells of the respiratory tree identical to those seen in premalignant lesions of cigarette smokers. Moreover, individuals, who smoke marijuana cigarettes, have a risk for lung cancer even greater than cigarette smokers only.
The smoke of pipes or cigars also increases the risk of lung cancer. However, the risk seems to be not as high as that of the cigarette. While the smoking of cigarettes for several years increases the risk for lung cancer up to 25 times, tobacco, cigars or pipes increase it at around 5 times, which nevertheless is a considerable increase in risk.
As with smoking, the risk of cancer with smoking marijuana, cigars or pipes also increases in proportion to the amount smoked and the time of use.
Occupational exposure
Occupational exposure
Some people work in areas or professions where there is frequent exposure to substances harmful to health. Exposure to some chemicals are associated with an increased risk of lung cancer, asbestos is among the most studied. Asbestos is used in various industrial areas, such as mining, construction, shipbuilding, railway construction, chemical and automotive, plumbing, fireproof coatings, soundproofing, fiber, cement tiles manufacturing and more than 2,500 other products. Banned in many countries, unfortunately asbestos is still legal in several Brazilian states due to a strong lobby in Congress.
Other substances of occupational exposure related to a higher risk of lung cancer include radon, arsenic, chromium, formaldehyde, nickel, ionizing radiation, metal dust and smoke of burning wood.
Workers exposed to these chemicals frequently, if they are smokers, have even higher risk of developing cancer. Just as an example, smoking and asbestos exposure increase the risk of lung cancer up to 60 times.
Family history
There is clearly a genetic predisposition to the development of lung cancer. This genetic influence is one of the factors that explain why not all heavy smokers develop cancer. Individuals with a first degree relative with lung cancer have a higher risk of developing it, especially if they are also smokers or submit any occupational exposure. The more relatives have had cancer or there are younger family members with cancer, the greater is the risk.
Diet
Several foods have been studied as potential protective against the development of lung cancer. The most studied include antioxidants, cruciferous vegetables (kale, cabbage, cauliflower, broccoli and Brussels sprouts) and vitamin B. Although there seems to be a link between the intake of these foods and the incidence of cancer, there are no data demonstrating real benefits of any diet.
