Risk Factors for Breast Cancer in Brazil

Sir—In a recent article by Gomes et al} they report the findings of a case-control study of risk factors for breast cancer in Brazil. They conclude that potential risk factors behave in the same way as demonstrated in the rest of the world and that the study provides clear documentation of 'breast cancer epidemiology' (p. 292) in Brazil. We would like to highlight some apparent oversights by the authors and to draw attention to the analytical complexities of breast cancer research especially when reproductive risk factors are being evaluated. They mention that Brazil shows an apparent contrast in that the breast cancer rates are relatively high in comparison with their Latin American neighbours. Previous research on breast cancer had already indicated the importance of conducting studies in Brazil because of such contrasts, which, if classified, could lead to a better understanding of breast cancer. However, they erroneously state that the study 'represents the first large hospital-based, case control study of risk factors for breast cancer conducted in Brazil' (p. 294).' Two other studies on breast cancer in Brazil have been published, the first in the early 1970s. The second relates to a case-control study on risk factors for breast cancer, and was undertaken in the early 1980s in Recife and Forteleza, two large cities of Northeast Brazil. The cases were breast cancer patients admitted to any of the several hospitals which deal with breast cancer in these two cities, to whom hospital and community matched controls were assigned. This study was larger than that of Gomes et al} and used interview based questionnaires instead of medical records. Results have subsequently been published. These results, presented by Kalache et al. suggested that age at last Full-Term Pregnancy (FTP) was an independent risk factor for breast cancer. This challenged the view that age at first FTP was the principal reproductive risk factor for breast cancer. The close similarity to the findings of a very different study, namely that of a large