Does margin width impact breast cancer recurrence rates in women with breast conserving surgery for ductal carcinoma in situ?

PURPOSE:Controversy remains regarding the optimal margin width for patients with ductal carcinoma in situ (DCIS) who undergo breast conserving surgery (BCS). METHODS:Women with a primary DCIS diagnosis were enrolled in a statewide population-based cohort from 1997 to 2006. Patients were surveyed every two years with follow-up data available through 2016. Surgical pathology reports were collected for 559 participants following breast conserving surgery. Multivariable Cox proportional hazard models evaluated relationships between locoregional recurrence (LRR) and margin width in the presence or absence of adjuvant radiation therapy while controlling for age, menopausal status and duration of endocrine therapy use. RESULTS:The majority of women in this study were over 50yo (74%), 34% had high grade disease, and 77% underwent radiation. The overall LRR rate was 12%. A LRR occurred in 46 women who had radiation (11%) and 23 women who did not undergo radiation (19%). Univariate analysis identified smaller margin width, younger age, premenopausal status, no radiotherapy, and shorter endocrine therapy use associated with LRR. Multivariable models demonstrated that close margins (< 2 mm) were associated with an increased risk of recurrence when compared to margins ≥ 2 mm in width whether women received radiation (HR 1.98 CI 0.87-4.54) or not (HR 1.32 CI 0.27-6.49), but confidence intervals were wide. CONCLUSIONS:In this study, patients with DCIS and close margins were less likely to experience recurrence after routine re-excision to margins greater than 2 mm.