Background & objectives: There is a paucity of data from India on the risk factors for lung cancer. In the present paper results of a case-control study on lung cancer undertaken at Chandigarh, north India, are described.
Methods: Two hundred and sixty five (235 men, 30 women) histologically confirmed patients of lung cancer and 525 (435 men, 90 women) hospital controls matched for age and sex were interviewed according to a pre-designed questionnaire. Effects of individual variables defining the various aspects of tobacco smoking, indoor and outdoor air pollution and occupational exposures were assessed using unconditional logistic regression models.
Results: Eighty nine per cent of men and 33 per cent of women among the patients were ever-smokers as compared to 60 per cent of men and 20 per cent of women among controls. The Odds Ratio (OR) for ever-smoking was 5.0 (CI 3.11-8.04) among men and 2.47 (CI 0.79-7.75) among women. Among the patients, men were found to smoke a higher average number of cigarette-equivalents per day, for longer duration and started at an earlier age as compared to controls. Smoking of bidi and hooka as well as cigarettes had similar ORs for cumulative consumption. ORs for female smokers were lower than those for male smokers. Cumulative exposure of > 45 yr in women to indoor air pollution from use of coal or wood for cooking or heating showed an OR of 1.43 (CI 0.33-6.30). Residence in urban areas did not entail an increased risk for developing lung cancer. Very few subjects studied were employed in high-risk occupations.
Interpretation & conclusions: Smoking (cigarettes or bidis) was the principle risk factor for causation of lung cancer among men. In women there could be several other risk factors besides smoking, as the association with smoking was not as strong.