Lung cancer in Greater Bombay: correlations with religion and smoking habits.

The resident population of Greater Bombay was analysed for the incidence of lung cancer and other variables of possible significance to lung cancer incidence. During a 10-year period from 1964-73, 2177 lung cancer cases (1861 males, 316 females) were registered, from a population pool consisting of 5.24 million persons (3.07 million males, 2.17 million females). The average annual incidence of lung cancer was 13.6 per 10(5) males but only 3.3 per 10(5) females, age-adjusted to the Standard World Population. The incidence in non-Parsi males (14.0) was almost double the figure in Parsi males (6.8). There was however no significant difference in incidence between non-Parsi (3.8) and Parsi females (3.3). Time-trend analyses did not reveal statistically significant differences in the incidence of lung cancer in any particular (male or female) age group. The data from death certificates for the same 10-year period 1964-73, showed that the age-adjusted rates (standardized to the world population) were 11.0 and 3.3 per 10(5), for males and females, in the total population. In a retrospective study, 792 males with lung cancer (42.6% of 1861 male cancer patients) for whom detailed smoking history is available, were matched for age and community with randomly selected controls, obtained from the voters list of the Greater Bombay Corporation, and significant statistical association was found between tobacco smoking and lung cancer. All smokers appear to be at high risk (16.8) compared with non-smokers. The relative risk in bidi smokers was however 19.3, even higher than in cigarette smokers (896). Hindu, Muslim and Christian smokers are apparently at identical risks. A dose-reponse relationship was found in bidi and cigarette smokers.