CIGARETTES AND LUNG CANCER

The relationship between lung cancer and cigarette smoking is much clearer and better known to most people than the relationship between food carcinogens and other forms of cancer. Cigarette smoking is the main cause of lung cancer; smoking produces this effect not only by generating cancer cells but by nourishing them, too.

It is known that the carcinogenic substances in cigarette smoke are the polycyclic aromatic hydrocarbon benzoalphapyren, aromatic amines, and nicotine and amine nitrite that yield the nicotine alkaloid. It is believed that a close relationship exists between the compounds of phenol and the growth of cancer cells.

Research is still in progress to ascertain whether the number of cigarettes smoked and the years of smoking are factors in producing cancer among habitual smokers. However, many researchers and experts agree that these factors are important contributors to cancer of the lung. For instance, in the case of pipe smoking, the risk for cancer can be calculated thus:

In other words, those who have been smoking since their adolescence are more prone to the danger of cancer owing to long years of exposure to the carcinogens involved in smoking. Statistics support these observations (see Table 16, p.139.)

In view of the increasing concern about second-hand smoke and the acceptance of anti-smoking campaigns throughout the world, there has been a decline in the number of smokers and total number of cigarettes smoked. In 1982 the ratio of smokers to non-smokers when seen against the total death rate was 2:1 for males and 1.3:1 for females. Investigations in more recent years revealed a slight decrease in the ratio for men to 1.6:1 in contrast to the slight increase in the ratio of 1.36:1 for women.

It has been established that smoking can cause carcinomatosis of the respiratory system and related structures in the form of lung cancer, laryngocarcinoma, and esophageal cancer. Recently, smokers in some countries whose second-hand smoke cause cancer among non-smokers are considered guilty of homicide! The close association between carcinomatosis and smoking is undeniable and will be widely discussed in the future as a major social issue.

Table 16. Ratio of standard death rates of lung cancer to number of cigarettes smoked