Prevalence of c-myc expression in breast lesions associated with microcalcifications detected by routine mammography

context and objective: genetic abnormalities in cell proliferation-regulating genes have been described in premalignant lesions. the aims here were to evaluate c-myc protein expression in non-palpable breast lesions associated with microcalcifications, detected by screening mammography, and to compare these results with histopathological, clinical and epidemiological variables. design and setting: analytical cross-sectional study, with retrospective data collection, in a university hospital in s？o paulo. methods: seventy-nine female patients who underwent routine mammography between 1998 and 2004 were studied. lesions classified by the breast imaging reporting and data system (bi-rads) as 4 or 5 underwent percutaneous biopsy using a large-core needle. ninety-eight lesions were studied anatomopathologically. paraffin blocks properly representing the lesions were selected for immunohistochemical analyses using the streptavidin-biotin-peroxidase technique with monoclonal mouse c-myc antibodies. results: among the 98 lesions, 29 (29.6%) contained malignant neoplasia; 40 (40.8%) had a positive immunohistochemical reaction for c-myc. when the groups were divided between lesions without atypias versus atypical lesions plus malignant lesions, 31.03% of the 58 lesions without atypias were positive for c-myc and 55% of the 40 malignant and atypical lesions (p = 0.018). comparing the atypical lesions with ductal carcinoma in situ versus the benign lesions without atypias, c-myc was present in 51.61% of the 31 atypical lesions and 31.03% of the benign lesions without atypias (p = 0.057). conclusion: c-myc protein was more frequently expressed in atypical and malignant lesions than in benign lesions without atypias. c-myc expression correlated with the presence of atypias (p = 0.018).