Risk Factors Associated to Residual Tumor in Re-excision for Positive Margins in Breast Conservative Surgery.

BACKGROUND Breast conservative surgery (BCS) is an adequate treatment for patients with early breast cancer. Local recurrence is associated with diverse factors. Our objective was to evaluate risk factors associated with finding residual tumor in patients with positive margins in BCS. METHODS Observational retrospective study, including patients diagnosed with breast cancer undergoing BCS between 2000 and 2016. Clinicopathological and treatment variables were collected. Main outcome was the finding of residual tumor on re-excision. Positive margins were defined as tumor present on ink. RESULTS Three hundred and six patients underwent BCS. Mean age was 57 ± 12.2 years. Positive margins were found in 84 (27.4%) patients, 15 (4.9%) had unknown margin status, and 207 (67.6%) had negative margins. Seventy-eight patients from the positive margin group and 23 patients from the unknown/negative margin group were reintervened. Residual tumor was present in 41% of patients with positive margins and in 45% of patients with negative margins (P = .192). In univariate analysis, overweight (P = .04) and positive axillary lymph nodes (P = .02) were associated with residual tumor on re-excision. In multivariate analysis, postmenopausal status was a protective factor (HR .047, P = .30). Mean follow-up was 58.4 months and mean local recurrence-free survival (LRFS) was 56.4 months (.1-203.2), with no difference regarding margin status or residual tumor. DISCUSSION Postmenopausal status was associated with a decreased rate of residual tumor in patients with positive margins. The presence of residual tumor on re-excision was not associated with a lower LRFS. These factors must be considered when positive margins are present in BCS.