The pill, estrogens, and the breast.Epidemiologic aspects

THE HALF-CENTURY THAT ESTROGENIC HOR-I mones have been used, fears have arisen at various times of their possible oncogenic effect on breast tissues.In fact, these fears were quite pronounced around 1933.Subsequent experience has tended to allay them, but with the advent of oral contraceptives they again came to the fore.There are indeed reasons for concern, since it is readily demonstrable that estrogen exerts effects on the breast.Perhaps the most suggestive evidence for a role of ovarian hormones in this disease is its rapid, exponential increase with age during the reproductive years, followed by a marked reduction in the rate of increase from the age of menopause.Such behavior is unlike that of most cancers, which tend to increase steadily into old age.Incidence rates for breast cancer from the Connecticut and California cancer registries were provided through the kindness of Dr. Barbara Christine and Mr. George Linder, respectively, The trend in age-specific rates has been carefully examined.There have been increases at certain ages in both areas, but the age groups which have shown an increase differ between areas.It is difficult to ascribe the increases to any particular factor.A direct approach to the problem would be afforded by either a prospective study or a case-control study.The former would be rendered difficult by the presumed long latent period and the large number of subjects needed.The most practical approach, the case-control study, has already yielded considerable epidemiologic information about Presented at the Second National Conference on Breast Cancer, Los Angeles.Calif.,