| Abstract: | A case-control study was conducted among Singapore Chinese women, comprised of 200 histologically confirmed cases of breast cancer and 420 hospital controls. Subjects were interviewed on family history of breast cancer, social and demographic characteristics, reproductive history, and diet one year prior to interview. Differences in risk factors were observed according to menopausal status. In the premenopausal group, the most consistently significant nondietary effect was an increased risk with late age at first birth. In postmenopausal women, the most consistent nondietary effects were increased risks with nulliparity, tall stature, high educational status, and a family history of breast cancer. In premenopausal women, the strongest dietary effects were low risks with high intakes of polyunsaturated fatty acids (PUFA),  -carotene, soya protein as a proportion of all protein, and a high risk with high red-meat intake. No dietary effects were observed in postmenopausal women. Examination of effects by 10-year age groups suggested that the differences in the effects of age at first birth, nulliparity, height, education, -carotene intake, and PUFA intake between premenopausal and postmenopausal women were at least partly attributable to age-related differences in the baseline distributions of these variables. The variation in the effects of red meat and soya protein appeared to be attributable mainly to menopausal status itself, which is consistent with the hypothesis that these factors operate on risk by way of hormonal mechanisms.Drs HP Lee and J Lee are with the Department of Community, Occupational and Family Medicine, National University of Singapore. Ms Gourley is with Gleneagles Hospital, Singapore. Dr Estève is with the International Agency for Research on Cancer, Lyon, France. Mr Duffy and Dr Day are with the Medical Research Council Biostatistics Unit, Cambridge, UK. Address correspondence to Dr HP Lee, Professor and Head, Department of COFM, National University of Singapore, Lower Kent Ridge Road, Singapore 0511. Funding for this study was provided by the International Agency for Research on Cancer. |
