What is the main cause of lung cancer?

Chemical carcinogens present in tobacco smoke.

(a) Exposure to ionizing radiation: While exposure to high levels of ionizing radiation, such as X-rays and gamma rays, is known to increase the risk of developing cancer, it is not the main cause of lung cancer. Ionizing radiation exposure is more commonly associated with other types of cancers, such as those affecting the thyroid or breast.

(b) Genetic factors: Genetic factors can play a role in predisposing individuals to certain types of cancer, including lung cancer. However, genetic factors alone are not the main cause of lung cancer. It is estimated that only a small percentage of lung cancer cases are directly linked to inherited genetic mutations.

(c) Consumption of alcohol: Alcohol consumption is not considered a significant cause of lung cancer. However, excessive alcohol consumption can contribute to the development of other types of cancer, such as those affecting the liver, esophagus etc.

(d) Chemical carcinogens present in tobacco smoke: This is the correct answer. The main cause of lung cancer, particularly non-small cell lung cancer, is exposure to chemical carcinogens present in tobacco smoke. The chemicals in tobacco smoke, including nicotine and various carcinogens can damage the cells lining the lungs and lead to the development of cancerous tumors.

Cigarette smoking is the leading risk factor for lung cancer, accounting for the vast majority of cases. It is estimated that approximately 85% of lung cancer cases are caused by smoking or exposure to secondhand smoke. Quitting smoking is the most effective way to reduce the risk of developing lung cancer.

In summary, the main cause of lung cancer is the exposure to chemical carcinogens present in tobacco smoke, primarily from cigarette smoking. Other factors, such as exposure to ionizing radiation or genetic predisposition, play a lesser role in the development of lung cancer compared to smoking.