Breast cancer in two populations with different levels of risk for the disease.

Caucasian women in Hawaii have a higher risk for breast cancer than women of Japanese ancestry. In order to determine to what extent known risk factors account for the difference in risk between the two groups, a case-control study was done from 1975 to 1980. A total of 183 Japanese and 161 Caucasian breast cancer cases were interviewed along with their respective controls. The findings suggested that a positive history of benign breast disease, a family history of breast cancer, late menopause, late age at first childbirth and early age at menarche did not fully account for the difference in breast cancer risk between Caucasian and Japanese women in Hawaii. Attention needs to be focused on other factors that are under environmental influence.