Background: Sentinel lymph node biopsy (SLNB) is recommended when mastectomy is performed for ductal carcinoma in situ (DCIS). The role of SLNB for women with DCIS who undergo mastectomy following one or more attempts at breast-conserving surgery (BCS) is uncertain. We examined the upgrade rate and SLNB yield in women who converted to mastectomy after one or more attempts at BCS for DCIS.
Methods: All patients who underwent one or more attempts at BCS prior to conversion to mastectomy with SLNB for DCIS were identified. Margin status as the indication for mastectomy was confirmed, and comparisons were made between patients with/without upgrade on final pathology.
Results: From February 2006 to November 2012, a total of 233 patients underwent completion mastectomy following one or more attempts at BCS for positive/close margins (median age 50 years; range 34-84). The median number of BCS attempts was 1 (range 1-4). Overall, 20 (9 %) patients were upgraded on final pathology; 15 (6 %) stage I, and 5 (3 %) stage II (three micrometastasis, two macrometastasis). In two of five cases with a positive SLN, invasive carcinoma was not identified in the mastectomy specimen. The only factor associated with any upgrade was the presence of micropapillary DCIS (80 vs. 55 %, with and without upgrade; p = 0.03).
Conclusion: In this cohort of patients with DCIS who converted to mastectomy for positive/close margins after one or more attempts at BCS, 18 (8 %) would have required second-stage axillary surgery had an SLNB not been performed, and in two (1 %) patients, the SLN provided the only evidence of invasion. These findings support the recommendation for SLNB at the time of completion mastectomy.