Risk Factors for Breast Cancer: A Case-Control Study

Kim, You Sah

Abstract

A hospit based case-control study was carried out to identify reproductive risk factors for breast cancer. Four-hundred-eighty-one breast cancer patients and 491 age-matched control patients examined between 1988 and 1994 were included in this study. Eleven reproductive risk factors were selected for comparison using cross tabulation and chi-square method, and univariate and multivariate logistic regression analyses were used to evaluate the odds ratios for the risk of breast cancer. The mean age of the breast cancer patients in this study was 47.5 years. Analyses demonstrated that nulliparous women had a higher risk for breast cancer (odds ratio 3.46, p=0.03) than women with 1-4 live births, and women who had an abortion during their first pregnancy had a slightly increased risk (odds ratio 1.86, p<0.01) than women who had normal deliveries, but the age at menarche and menopause did not have any influence on the risk of developing breast cancer. Although there were similarities in risk factors between Western women and women in this study, such as a higher risk for nulliparous women, two key factors were found to contrast with those of Western women. First the mean age of breast cancer patients in this study was only 47.5 years. Second, the age of menarche and menopause of these women did not have any influence on the risk of breast cancer.