Importance of Surgical Margin Status in Ductal Carcinoma In Situ

Surgical margin status remains an area of controversy in patients with ductal carcinoma in situ (DCIS). In the presented analysis, the effect of final surgical margins and re-excision were analyzed in a cohort of patients who underwent breast conservation surgery followed by whole breast radiation and a tumor bed boost. This single-institution experience showed no difference in local recurrence rates in an examination of patients with negative versus close or positive margins likely because of the limited number of events. Regardless, obtaining a clear margin with no ink at resection should remain the standard management for these patients except in exceptional circumstances in which a patient refuses further surgery. Better identification of patients who do not require re-excision for DCIS is necessary. Background: The purpose of the study was to identify the effect of final surgical margin (SM) status and re-excision on outcomes in patients with ductal carcinoma in situ (DCIS) who underwent breast conservation therapy (BCT). Patients and Methods: The study population consisted of women diagnosed with DCIS who underwent BCT between 1989 and 2014. All women received adjuvant whole breast radiation and a boost. The primary end point was local control (LC). Final SMs were defined according to margin width: negative SM was defined as > 2 mm, close SM was defined as > 0 to <= 2 mm, and a positive SM was defined as tumor on ink. The Cox proportional hazards model was used to determine predictors of outcomes on multivariable analysis. Actuarial incidence of LC was estimated using the Kaplan-Meier method. Results: A total of 498 patients were included; 400 patients had a final negative SM, 87 had a close SM, and 11 had a positive SM. A total of 172 patients received adjuvant hormonal therapy, 265 patients required >= 1 reexcision. Patients with positive or close SMs were more likely to receive a radiation dose > 60 Gy (P < .001) and undergo re-excision (P < .01). The 10-year LC rates were not significantly different between patients with a negative (93.5%), close (91.8%), or positive (100%) SM (P = .57). There was no difference in LC in patients who underwent reexcision for initial close or positive SMs (P = .55). Conclusion: This single-institution experience showed that risks of local recurrence remain poorly characterized. Re-excision and whole breast radiation with boost resulted in excellent LC for women with DCIS. Trials aimed at personalized deintensified local therapy are warranted.