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Causes of Lung Cancer

Following are the well recognised risk factors for Lung Cancer:

  • Smoking
  • Genetic risk
  • Asbestos
  • Radon gas
  • Other causes



Smoking causes Lung Cancer

Cigarette smoking is known to be the cause of most lung cancers. The more you smoke, the greater your risk of developing lung cancer. Lung cancer is also more likely to develop in people who start smoking at a young age. People who don't smoke can also develop lung cancer, although this is much rarer. Filtered and low-tar cigarettes may slightly reduce a person's risk of developing cancer, but the risk is still far greater than that of a non-smoker.

Lung cancer has always been more common in men, particularly those over 40, as more men used to smoke than women. However, as more women have started smoking, the number of women developing lung cancer has gone up considerably.

Stopping smoking

If a person stops smoking, the risk of lung cancer falls quite quickly. After about fifteen years, that person's chances of developing the disease and cancer are slightly higher than the one who has never smoked.

Passive smoking

It now appears that breathing in other people's cigarette smoke (passive smoking) increases the risk of lung disease and cancer. The risk is still much less than for the one who smokes himself.

Pipes and cigars

Although pipe and cigar smokers have a lower risk of lung cancer than cigarette smokers, they are still at a much greater risk than non smokers.


Smoking cannabis may also increase the risk of developing lung cancer. Although less is known about the harmful effects of smoking cannabis, it is believed to cause similar damage to the cells in the lungs as smoking tobacco.

Genetic risk

In some families, smokers may be more likely to develop lung cancer due to inherited faulty genes.


People who have been in prolonged or close contact with asbestos have a higher risk of lung cancer, especially if they smoke. Asbestos and tobacco smoke act together to increase the risk. Many people have been in contact with asbestos during their working lives. Low-level exposure increases the risk of lung cancer only slightly (compared to the risk from smoking), while heavy exposure may result in a much higher risk.

Asbestos exposure also increases the risk of mesothelioma, a cancer of the membranes which cover the lungs.

Radon gas

In some parts of the UK, such as the West Country and the Peak District, a naturally occurring gas called radon can pass from the soil into the foundations of buildings. It is now thought that in high concentrations this gas may increase the risk of developing lung cancer.

Other causes

Contact with certain chemicals and substances such as uranium, chromium and nickel
can cause lung cancer, but these are very rare causes. Air pollution has been suggested as a cause of lung cancer, but this is difficult to prove.

Lung cancer is not infectious and cannot be passed on to other people.

How common is the Lung Cancer in India?

Lung cancer is the most common cancer among men from the Indian subcontinent and is the number one killer of men dying due to any cancer related affliction. For women the incidence of Lung Cancer ranks ninth among all other cancers. Considering all the cancers among men and women together, Lung Cancer ranks number four in India1

In India, between the years 2001-2003, across five urban centers - Mumbai, Delhi, Chennai, Bhopal and Bangalore, and one rural center - Barshi, a total of 4,137 cases of Lung cancer were registered (9.4% of all cancers) for males across all age groups; while 1,140 cases of Lung cancer were registered (2.55% of all cancers) for females across all age groups. Considering all men, women and children with all types of cancers together, a grand total of 5,277 cases of Lung cancer (6% of all cancers) were registered at the six centers mentioned above, between the year 2001-20032.

The TATA Memorial Hospital (T.M.H.) in Mumbai, India registered a grand-total of 19,127 cases of all types of cancer patients in the year 2006 for men, women and children combined, out of which 1,064 (5.6% of the total cases) were diagnosed with the Lung cancer. Out of the total 1,064 patients diagnosed with Lung cancer, mentioned above at the T.M.H., 812 (76%) were males and 252 (24%) were females3.