Axillary Recurrence in Sentinel Lymph Node Negative Mastectomy Patients at 16 Years Median Follow Up: Natural History in the Absence of Radiation

Background: Axillary recurrence following lumpectomy with a negative sentinel lymph node biopsy (SLNB) is rare, possibly due to routine use of whole breast radiation. In this study, we characterized the rate of any axillary recurrence among mastectomy patients with a negative SLNB and no adjuvant radiation therapy. Methods: We identified women who underwent mastectomy with SLNB for early-stage breast cancer (1999-2005) and included patients with pathologically negative nodes and no axillary dissection or adjuvant radiation. The primary outcome was ipsilateral axillary recurrence. Results: A total of 234 women, median age 50 years, underwent 242 mastectomies. Histology showed 112 (46%) invasive cancers, 16 (7%) ductal carcinoma in-situ (DCIS) with microinvasion, and 114 (47%) pure DCIS. Cancers were predominantly estrogen receptor positive (59%) and moderate (41%) or high grade (32%). A mean of 2 final sentinel nodes were excised (range 1-6) and 21 patients (9%) had isolated tumor cells on SLNB pathology. At 16 years median follow up (range 1-22 years), 3 patients (1.2%) developed an isolated axillary failure, and 1 had concurrent axillary and chest wall recurrences (total axillary recurrence rate 1.7%). Three of four axillary recurrences occurred in patients with moderate or high-grade estrogen receptor-positive DCIS without invasion on mastectomy histology. Median time to axillary recurrence was 70.5 months (range 29-132 months). Conclusions: Axillary recurrence is rare after a negative SLNB, even in the absence of adjuvant radiation. This supports the safety of forgoing additional surgery or radiation to the axilla in the early-stage breast cancer and a negative SLNB.