| The relationship of estrogen replacement therapy (ERT) and breast cancer in postmenopausal women was examined in a case-control study conducted in Cali, Colombia during 1990. The data included 125 cases identified through the population-based Cancer Registry of Cali. Eligible cases were postmenopausal women between the ages of 40 and 65, diagnosed between 1985 and 1990 with a histologically confirmed carcinoma of the breast and who resided in Cali. One hundred twenty-five controls were matched to cases based on age and referral clinic. Information on ERT use and known risk factors for breast cancer was obtained through personal interviews. Type of ERT was assessed by showing pictures of estrogen packages.;After adjusting for education, age at first delivery, breast feeding, family history of breast cancer, and trimming fat from meat, the matched odds ratio for ERT use and breast cancer was 2.4 (95% CI 0.9-6.2). Risk of breast cancer increased with duration of use; cases were 6.3 times more likely than controls to have used ERT for 2 years or more. Cases were 3.9 times more likely to have been former ERT users (95% CI 1.2-12.4); 3.4 times more likely to have begun using ERT 5 or more years prior to diagnosis (95% CI 1.0-10.8); and 3.3 times more likely to have begun using ERT prior to age 45 (95% CI 0.8-13.6).;An accurate measurement of the magnitude of women's exposure to estrogens was difficult to assess due to the changes in estrogen dosages over the last 20 years. This does not, however, erase the finding of a positive association between breast cancer and ERT, which warrants further investigation.;Twenty percent of the study population had ever used ERT for at least 6 months: 27.2 percent of the cases and 15.2 percent of the controls, resulting in a matched crude odds ratio of 2.0 (95% confidence interval, CI, 1.1 to 3.7). In this study, most of the risk factors identified were consistent with those found in the literature including high education, family history of breast cancer, nulliparity, delayed first birth, and not breast feeding. |
