The author of this article: Pan Yi 丨 Guangdong Provincial People's Hospital, Chief Physician of the Department of Radiation Therapy
Regarding the pathogenesis of lung cancer, it is still not completely clear, but scientists have found some "clues" related to lung cancer through long-term observations.
1. Age
Why are there so few records of cancer in our ancestors? Why don't cats and dogs suffer from cancer? Maybe they haven't lived to be old enough to get cancer. Cancer is an age-related disease, and the same is true for lung cancer.
The latest cancer data released by the National Cancer Center in China show that the incidence of cancer gradually increases with age, growing rapidly after the age of 40 and peaking at the age of 80 [1].
Second, heredity
We carry a lot of genetic information inherited from our parents, like labels that accurately distinguish each person's characteristics.
Lung cancer is not a genetic disease, but there is a certain "genetic susceptibility", that is, the tendency of genetic factors to develop diseases, and the acquired environment has a great impact on its occurrence.
The oncogenes closely related to lung cancer mainly include ras and myc gene families, cerbB-2, Bcl-2, c-fos and c-jun genes; related tumor suppressor genes include p53, Rb, CDKN2, FHIT genes, etc.; molecular changes related to the occurrence and development of lung cancer also include abnormalities in mismatch repair genes such as hMSH2 and hPMS1, and telomerase expression.
Image source: Stand Cool Helo
3. Smoking
As the saying goes, "After a meal, a cigarette, race through the living gods". In fact, long-term smoking will really see the gods sooner. Benzopyrene, nicotine, nitrosamines and a small amount of radioactive elements such as polonium in the smoke have carcinogenic effects.
There are several or dozens or even hundreds of carcinogens in a mouthful of smoke. A variety of cigarettes, cigars and pipes are at risk of carcinogenesis.
Compared with non-smokers, smokers are on average 4 to 10 times more likely to develop lung cancer and heavy smokers are 10 to 25 times higher[2][3][4][5].
There is a clear quantitative relationship between smoking and lung cancer, and the younger the age, longer and greater the amount of smoking, the higher the incidence of lung cancer.
In families where the husband smokes and the wife does not smoke, the risk of lung cancer is twice that of the wife in the couple's non-smoking family, and the risk increases with the husband's smoking.
The incidence of lung cancer in U.S. men increased dramatically in the 1950s as a result of an increase in the number of smokers in the early 20th century.
In the past two decades, due to the popularization of the concept of smoking harm to health, the implementation of comprehensive tobacco control, and early diagnosis and treatment, the lung cancer mortality rate in the United States has decreased by 43% from 1990 to 2014, and the lung cancer mortality rate in women has decreased by 17% from 2002 to 2014 [6].
Fourth, air pollution
PM2.5 is a topic of concern, and studies have shown that PM2.5 can enter the alveoli, which not only affects the exchange of gas in the lungs, but also penetrates the lungs and sneaks into the bloodstream, bringing health problems.
The rate of lung cancer, particularly adenocarcinoma, is very high in people with long-term exposure to PM2.5 [7]. Indoor coal use, exposure to soot or incomplete combustion, and oil fumes released by heating during cooking are also risk factors for lung cancer.
5. Occupational carcinogenic factors
Occupational factors that have been identified asbestos, arsenic, chromium, nickel, beryllium, coal tar, mustard gas, trichloromethether, chloromethyl ether, heating products of tobacco, radon gas, ionizing radiation and microwave radiation produced when radioactive substances such as uranium and radium decay.
These factors can increase the risk of lung cancer by 3 to 30 times. Among them, asbestos is a recognized carcinogen, and the lung cancer mortality rate of smokers exposed to asbestos is 8 times that of non-contact smokers.
Sixth, diet and nutrition
Some studies have shown that eating fewer vegetables and fruits containing β increases the risk of lung cancer, while eating more green, yellow and orange vegetables and fruits containing β carotene and foods containing vitamin A can reduce the risk of lung cancer, and this protective effect is particularly pronounced for people who are smoking or who have smoked before.
However, some studies have concluded the opposite, suggesting that long-term supplementation with β-carotene and vitamin A in large quantities increases the incidence of lung cancer [8]. This area is still controversial.
The occurrence of lung cancer is often complicated, and we are temporarily powerless in the face of genetics, age and other factors. However, measures such as smoking control and smoking cessation, avoiding high-risk occupational exposures, and protecting against smog days can reduce the relative risk. Regular physical examination and regular screening of lung cancer in high-risk groups are conducive to early diagnosis and treatment, and the prognosis is relatively good.
Co-review: Guangdong Provincial People's Hospital Guangdong Provincial Lung Cancer Research Institute Dr. Chen Zhiyong Dr. Zhang Jiatao
Co-author: Dr. Ma Yue, Department of Oncology, Renji Hospital, Shanghai Jiao Tong University
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