Outcomes Following Breast-Conserving Surgery for Positive Radial Margins: A Five-Year Longitudinal Study

IntroductionBreast-conserving surgery (BCS) is the treatment of choice for ductal carcinoma in situ (DCIS) and earlystage invasive carcinoma.BCS is associated with a re-excision rate of 17-20%.The aim of this study is to determine the incidence of residual disease in patients requiring re-excision of margins following BCS, assess margin positivity towards the nipple, and evaluate long-term oncological outcomes. MethodsThis was a single-centre retrospective study that included all patients who had involved or close margins following BCS between July 2013 and November 2018.Data on histology, treatment following subsequent surgery, and follow-up information were collected from medical records. ResultsOut of the 1,779 patients, 190 (10.6%) underwent further surgery for positive margins; 49 had DCIS, 141 patients had invasive carcinoma; and 73 (38.6%) patients had residual disease in the re-excised margin(s).The incidence of residual disease in the excised specimen was significantly higher for DCIS (36/49) than for invasive disease (37/141) (p < 0.0001).Overall, 32 (17%) needed a second re-excision for positive margins.Radial margin involvement towards the nipple was more commonly seen in DCIS than in invasive cancers (p = 0.0044).The overall mastectomy rate for the entire cohort was 7.3%.During a median follow-up of 47 months, seven (3.7%) local, one (0.5%) regional, and five (2.6%) distant recurrences were observed.Local recurrence was significantly higher in patients with pure DCIS (10.2%) with positive margins (p = 0.00278). ConclusionThe rates of second re-excision, margin positivity towards the nipple, and local recurrence were significantly higher in patients with pure DCIS.Patients should be counselled pre-operatively regarding these outcomes when undergoing breast-conserving procedures.