Cancers of the cervix uteri and breast: changes in incidence rates in Bombay over the last two decades.

The age-adjusted incidence rate of cervical cancer in Bombay has decreased over the last 20 years, whereas over the same period that of breast cancer increased slightly. Studies indicate that the incidence of cervical cancer is lower in successively later-born cohorts, but no cohort effect has been observed for breast cancer. Age at marriage is an important factor in the etiology of both these cancers, and it is plausible that the decrease in cervical cancer has resulted from the increase in age at marriage of women over the last 20 years in the city. The changing pattern of incidence of cancer for women in Bombay, among whom the incidence of breast cancer is the highest of all forms of cancer, indicates that, from a long-term perspective, cancer control programmes in India as a whole should aim at minimizing the risk of both cervical and breast cancer.