Breast cancer risk factors in African-American women: the Howard University Tumor Registry experience.

This retrospective case-control study examines risk factors for breast cancer in African-American women, who recently have shown an increase in the incidence of this malignancy, especially in younger women. Our study involves 503 cases from the Howard University Hospital and 539 controls from the same hospital, seen from 1978 to 1987. Using information culled from medical charts, an analysis of various factors for their effect on breast cancer risk was made. The source of data necessarily meant that some known risk factors were missing. Increases in risk were found for known risk factors such as decreased age at menarche and a family history of breast cancer. No change in risk was observed with single marital status, nulliparity, premenopausal status, or lactation. An increased odds ratio was found for induced abortions, which was significant in women diagnosed after 50 years of age. Spontaneous abortions had a small but significant protective effect in the same subgroup of women. Birth control pill usage conferred a significantly increased risk. It is of note that abortions and oral contraceptive usage, not yet studied in African Americans, have been suggested as possibly contributing to the recent increase in breast cancer in young African-American women.