Evolution in practice patterns of axillary management following mastectomy in patients with 1–2 positive sentinel nodes

Purpose: The optimal management of breast cancer patients with a positive sentinel lymph node (SLN) who undergo mastectomy remains controversial. This study aimed to describe treatment patterns of patients with positive SLNs who undergo mastectomy using a large population-based database. Methods: The NCDB was queried for cT1–2N0 breast cancer patients treated with mastectomy between 2006 and 2014 who had 1-2 positive SLNs. Patients receiving neoadjuvant chemotherapy were excluded. Axillary management included SLN dissection (SLND) alone, axillary lymph node dissection (ALND), post-mastectomy radiation (PMRT) alone, and ALND + PMRT. Trends of axillary management and patient characteristics were examined. Results: Among 12,190 patients who met study criteria, the use of ALND dropped with a corresponding increase in other approaches. In 2006, 34% of patients had SLND alone, 47% ALND, 8% PMRT and 11% ALND + PMRT. By 2014, 37% had SLND, 23% ALND, 27% PMRT and 13% ALND + PMRT. Patients who underwent SLND alone were older (mean 60.6 years) with more comorbidities (Charlson–Deyo score > 2), smaller primary tumors (mean 2.1 cm), well-differentiated histology, hormone receptor-positive, HER2-negative tumors, without lymphovascular invasion (all P values < 0.01). Treatment with SLND alone was more likely if patients had only one positive SLN (P < 0.001) or micrometastatic disease (P < 0.001), and were treated at community centers compared with academic centers (P < 0.001). Conclusions: The management of breast cancer patients undergoing mastectomy with positive SLNs has evolved over time with decreased use of ALND and increased use of radiation. Some patient subsets are underrepresented in recent clinical trials, and therefore, future trials should focus on these patients.