Factors related to the incidence of lung cancer

The cause and pathogenesis of lung cancer are not clear. It is currently believed that the incidence of lung cancer is mainly related to the following factors:

1. Smoking Active smoking is recognized as the number one risk factor for lung cancer. Among them, the type of smoking, smoking intensity, continuous smoking time, tar content in tobacco, and time to quit smoking are all related to the occurrence of lung cancer. Cigarette smoking is the most harmful. Compared with non-smokers, its relative risk is 14, while the relative risk of pipe smoking or cigar smoking is only 5.8. For those who smoke 1 to 9 cigarettes a day, the relative risk is 10; for those who smoke 10 to 20 cigarettes, it is 16.4; for those who smoke more than 21 cigarettes, it is 17.3 or higher. Continuous smoking time is the most important factor affecting lung cancer. The ratio of lung cancer incidence in people who smoke for 45 years, 30 years, and 15 years is 100:20:1. The higher the tar content in tobacco, the higher the incidence of lung cancer. It may be due to the different sensitivity of the two sexes to tar. The influence of tar content on the incidence of lung cancer in women is much higher than that in men. People have always believed that quitting smoking can reduce the incidence of lung cancer. After research, it was found that the reduction in incidence caused by quitting smoking is mainly caused by reducing the continuous smoking time. The incidence of lung cancer in those who have quit smoking does not decrease, but remains at the same rate as the duration of their smoking.

Passive smoking is also one of the causes of lung cancer. In a couple, if the husband smokes, the woman's risk of lung cancer increases by so%. The incidence rate increases with the amount of smoking by the man, and decreases when the man stops smoking. Various evidences show that passive smoking can increase the incidence of lung cancer, but most research results show that its relative risk is less than 2.

2. Occupational factors: People working in metallurgical mining (such as aluminum, arsenic, beryllium, steel, nickel, asbestos, silicon, radium), petrochemical (such as coal tar, coal gasification), and paint industries are more likely to develop lung cancer than ordinary people.

3. Ionizing radiation Large doses of ionizing radiation can cause lung pain, and different rays have different effects. In 1978, the United States reported that about 49.6% of the radiation received by the general population came from nature, 44.6% was medical radiation, and about 36.7% came from X-ray diagnosis.

4. Nutrition and diet Vitamin A and β-carotene can inhibit the carcinogenic effect of chemicals. However, there are also reports with different views, which deny the anti-cancer effect of β-carotene. Whether fruits and vegetables contain anti-cancer substances needs further research.

5. Air pollution Mild air pollution has little effect on the incidence of lung cancer, but severe pollution can have a significant impact.