Occurrence of breast cancer in relation to diet and reproductive history: a case-control study in Fukuoka, Japan.

An epidemiologic study on breast cancer in relation to diet and reproductive history was conducted with 3 populations at different levels of risk for the disease: Japanese in Fukuoka, Japan (low risk), Japanese in Hawaii (intermediate risk), and Caucasians in Hawaii (high risk). This report describes the Fukuoka portion of the study. We interviewed 212 patients with histologically confirmed breast cancer and an equal number each of hospital and neighborhood controls to determine risk factors for the disease. The results indicated that "overnutrition" (a high-fat and high-animal protein diet) was not statistically associated with the disease. As noted in previous studies, age at the first birth was positively related to the disease; those women who gave birth to their first child when they were 35 or more years of age showed a relative risk of 5.0 compared with those giving birth at less than 20 years of age. A past history of both natural abortion and of benign breast disease were significantly associated with the disease. On the whole, the results obtained from this Fukuoka portion of study were in good agreement with those from the Hawaii study during which Japanese and Caucasians in Hawaii were investigated.