Impact of Axillary Dissection Among Patients With Sentinel Node-Positive Breast Cancer Undergoing Mastectomy.

BACKGROUND Results of the American College of Surgeons Oncology Group (ACOSOG) Z0011 trial supports omission of completion axillary lymph node dissection (CLND) after breast-conservation surgery with a positive sentinel lymph node biopsy (SLNB). We hypothesized that CLND also does not impact outcomes in women with clinically node-negative (cN0), pathologically node-positive breast cancer undergoing mastectomy. MATERIALS AND METHODS A single-institution retrospective review was performed of patients with SLN-positive breast cancer treated from July 1999 through May 2018. Clinicopathologic and outcome data were collected. Patients with SLNBs were compared with those receiving SLNB and CLND. The Kruskal-Wallis, chi-square, and Fisher exact tests were used to assess for differences between continuous and categorical variables. The log-rank test was used for time-to-event analyses, and Cox proportional hazards models were fit for locoregional and distant recurrence and overall survival (OS). RESULTS Of 329 patients with SLN-positive breast cancer undergoing mastectomy, 60% had CLND (n=201). Median age at diagnosis was 53 years (interquartile range [IQR], 46-62 years). The median number of SLNs sampled was 3 (IQR, 2-4), and the median number of positive SLNs was 1 (IQR, 1-2). Patients receiving CLND had higher tumor grades (P=.02) and a higher proportion of hormone receptor negativity (estrogen receptor, 19%; progesterone receptor, 27%; both P=.007). A total of 44 patients (22%) had increased N stage after CLND. Median follow-up was 51 months (IQR, 29-83 months). No association was found between CLND and change in OS and locoregional or distant recurrence. Completion of postmastectomy radiotherapy was associated with improved OS (P=.04). CONCLUSIONS CLND is not significantly correlated with reduced recurrence or improved OS among patients who have cN0, SLN-positive breast cancer treated with mastectomy. CLND was significantly correlated with receipt of adjuvant systemic therapy. Completion of postmastectomy radiotherapy was associated with improved OS.