Socioeconomic status, lactation and breast cancer risk of parous women in Taiwan

The objective of this study was to evaluate effects of socioeconomic status and lactation on breast cancer of parous women in Taiwan. A total of 102 parous incident cases of female breast cancer in Taipei City were recruited from National Cancer Registry. Another 102 community parous controls individually matched with each case on residential area and age (within five years) were randomly selected from household registration profiles. Socioeconomic status including ethnic group, schooling years, family income, and religion, reproductive risk factors, lactation and body size risk factors for breast cancer were collected from a structured questionnaire interview. Conditional logistic regression was used to estimate the multivariate-adjusted odds ratio of each risk factor. Family income was positively and significantly associated with breast cancer, showing a significant dose-response trend. High parity above three showed a significant protective effect. There was a prominent protective effect from breast feeding. The longer the duration, the smaller the risk of breast cancer. The protective effect of breast feeding was significant only in women who had more than three deliveries.