Risk factors for positive margins in conservative surgery for breast cancer after neoadjuvant chemotherapy.

Background: Breast conservative surgery after neoadjuvant chemotherapy intends to remove any residual tumor with negative margins. The purpose of this study was to analyze the preoperative clinical-pathological factors influencing the margin status after conservative surgery in breast cancer patients receiving neoadjuvant chemotherapy.

Methods: A retrospective study of 91 breast cancer patients undergoing neoadjuvant chemotherapy (92 breast lesions) during the period 2006 to 2013. A Cox regression analysis to identify baseline tumor characteristics associated with positive margins after breast conservative surgery was performed.

Results: Of all cases, 71 tumors were initially treated with conservative surgery after neoadjuvant chemotherapy. Pathologic exam revealed positive margins in 16 of the 71 cases (22.5%). The incidence of positive margins was significantly higher in cancers with initial size >5cm (P=.021), in cancers with low tumor grade (P=.031), and in patients with hormone receptor-positive cancer (P=.006). After a median follow-up of 45.2 months, 7 patients of the 71 treated with conservative surgery had disease recurrence (9.8%). There was no significant difference in terms of disease-free survival according to the margin status (P=.596).

Conclusions: A baseline tumor size >5cm, low tumor grade and hormone receptor-positive status increase the risk for surgical margin involvement in breast conservative surgery after neoadjuvant chemotherapy.