Positive margins following breast cancer tumorectomy. Can we predict the occurrence of residual disease?

Aims and background. In conservative early stage breast cancer surgery, the sample's margins are directly related to relapse, and positive or close margins indicate the need for additional surgery. Since the range of residual disease in secondary surgeries and the related pathological factors are highly variable, we intended to evaluate the number of additional surgeries due to compromised margins and identify the percentage of residual disease and factors related to it. Methods. We retrospectively analyzed the clinical records of 659 tumorectomy or needle localization surgery patients with breast carcinoma at the Hospital Universitario Austral in Buenos Aires, Argentina, between December 2000 and December 2012. The variables considered were age, type of surgery, type of margin, tumor size, histological grade, extensive intraductal component and immunohistochemical profile. We investigated how they related to the presence of residual disease. Results. We identified 68 patients (10%) who were reoperated because of positive (75%) or close (25%) margins. Residual disease was identified in 68% of them; the positive (66%) and close (70%) margin ratio was similar. The individual analysis of variables was statistically significant only for tumors larger than 3 cm (Pearson's chi square [1] = 6.7194; P = 0.0095; relative risk = 1.56 [95% CI 1.09-2.21]) with an association between age and tumor size: Pearson's chi square (1) = 3.8984; P = 0.0483; relative risk = 1.56 (95% CI 1.09-2.21). Conclusions. The need for second surgery due to compromised margins is not common, with variable residual tumor identifying ranges. Some pathological factors can predict the persistence of residual disease. In our series, tumor size >3 cm was the variable identified as an independent predictor.