Résumé
OBJECTIVE: To assess the performance of mammography in the detection of nonpalpable breast lesions according to the BI-RADS categories, to analyse the risk factors for breast cancer and to discuss the importance of clinical data on mammography assessment. MATERIAL AND METHODS: Retrospective study with 650 women who underwent preoperative lesion localization, followed by surgical removal of the suspect lesion. The mammography results for these patients, classified according to BI-RADS (fourth edition), were correlated with the anatomical-pathological findings, evaluating the positive predictive value for each category. The risk factors to breast cancer were analiyzed and discussed toghether with BI-RADS classification. RESULTS: Of the total of 650 cases, 59 percent (n = 384) had benign lesions, 10.46 percent (n = 68) had atypical lesions and 30 percent (n = 198) had malignant lesions in the histological study. Microcalcifications were the most frequent finding in the mammograms, observed in 436 patients (67 percent). The positive predictive values for categories 3, 4 and 5 were 13.88 percent, 26.76 percent and 82.35 percent, respectively. On multivariate analysis, only older age and lymph node enlargement on physical examination were associated with malignant results on histology. CONCLUSION: The study showed that the BI-RADS category is a very important tool in the diagnosis of breast cancer. There was a high frequency of malignant findings on lesions classified in BI-RADS category 3, which is problably related to the high prevalence of breast cancer risk factors in our population.