The relationship between lung cancer and smoking

The exact cause of lung cancer is still unknown. After years of extensive research, a large amount of survey data from various countries shows that the cause of lung cancer is closely related to smoking, and the increase in the incidence of lung cancer is parallel to the increase in cigarette sales.

Cigarettes are rich in benzopyrene and other carcinogens. Experimental animals that inhale cigarette smoke or apply tar can develop respiratory and skin cancer. The incidence rate is higher for those who smoke more. Data show that the lung cancer incidence rate for those who smoke more than 25 cigarettes a day is 2.27/1,000 person-years, for those who smoke 15-24 cigarettes a day is 1.39/1,000 person-years, and for those who smoke 1-14 cigarettes a day is 0.57/1,000 person-years.

At the end of the last century, with the increasing number of female smokers in Western European countries, the incidence of lung cancer in female patients also increased significantly. Among clinically diagnosed lung cancer cases, those who smoke more than 20 cigarettes a day for more than 30 years account for more than 80%. In the past 20 to 30 years, the smoking situation in my country has been very serious, with nearly 300 million people having the habit of smoking. The smoking rate of male adults in large cities such as Beijing, Tianjin, and Shanghai is nearly 50%, and that of females is nearly 5%. There are also many smokers among teenagers. Long-term smoking can cause bronchial mucosal epithelial cell hyperplasia, squamous metaplasia, and induce squamous cell carcinoma or undifferentiated small cell carcinoma. Although non-smokers can also suffer from lung cancer, adenocarcinoma is more common.