A Case Control Study of Breast Cancer (Part2) : Analysis of Environmental Factors Stratified by Menopausal Status

A case-control study was performed to investigate the risk factors for breast cancer of women in Hokkaido, Japan. These were 152 cases of patients treated between October 1986 and January 1989, in the Department of Surgery (Section 1), Sapporo Medical College. They were inter-viewed face-to-face. Controls were 304 women randomly selected from telephone directories. They were matched with index cases for age and menopausal status. Telephone interviews were conducted with them. For statistical analysis, Mantel-Haenszel method and conditional logistic regression analysis were employed. All of the analytical methods found the following factors to be significant. Eating beef, eating chicken, and drinking wine before menopause, and eating meat everyday after menopause were more likely to be associated with breast cancer. Before menopause, eating fish more than three times a week was more likely to reduce the risk of breast cancer. These factors seem to be firmly relevant to the development of breast cancer. As in our first report, we have considered the different risk factors in the periods before and after menopause. Since environmental factors can change, further investigation should be perfor-med in the future