Breast cancer and religion in greater Bombay women: an epidemiological study of 2130 women over a 9-year period.

The resident female population of Greater Bombay consists of women professing different religious faiths, between which the frequency of breast cancer varies to a great extent. During the 9-year period 1964 to 1972 inclusive, a total of 2130 women with breast cancer were seen, with break-down by religion as follows: Hindus (1259), Muslims (306), Christians (264), Parsi (Zoroastrians) (226), Jains (25), Buddhists (26) and others (24). The average annual age-adjusted (world population) incidence rates, however, were found to be 48.5 and 18.2 per 100,000 in the Parsis and non-Parsis respectively, with an average of 19.9 per 100,000 for the total population. For reasons not yet clear, in every age group the incidence rate in Parsis was 2 to 3 times higher than in the non-Parsis. Time-trend analyses of our data do not reveal any statistically significant increase or decrease in the incidence of breast cancer in any particular age group. Data from death certificates for the same 9-year period show that the age-adjusted mortality rate (world population) is 9.2 per 100,000/year.