Optimizing Axillary Management in Clinical T1-2N0 Mastectomy Patients with Positive Sentinel Lymph Nodes

Following publication of the AMAROS trial, we sought to optimize axillary lymph node dissection (ALND) or postmastectomy radiation therapy (PMRT) + axillary radiation (AxRT) utilization in cT1-2N0 patients with 1-2 positive sentinel lymph nodes (SLNs) after mastectomy.

In November 2015, our multidisciplinary group implemented a protocol to omit intraoperative SLN evaluation for mastectomy patients with cT1-2N0 breast cancer likely to be recommended PMRT if found to have 1-2 positive SLNs (age ≤ 60 years and/or high-risk features defined as estrogen receptor-negative and/or positive for lymphovascular invasion). We prospectively evaluated axillary management, short-term complications, and oncologic outcomes in patients with 1-2 positive SLNs.

From November 2015 to December 2018, 479 of 560 (85%) cT1-2N0 breast cancers treated with mastectomy were potential candidates for PMRT. Intraoperative SLN evaluation was omitted in 344 (72%), thus following the protocol. Overall, 121 cases had 1-2 positive SLNs: 17 (14%) were managed with observation, 5 (4%) PMRT alone, 59 (49%) PMRT + AxRT, 16 (13%) ALND alone, and 24 (20%) ALND + PMRT. Protocol compliance resulted in less ALND (8% vs. 24%) and less ALND + PMRT (9% vs. 41%, p < 0.01). At median follow-up of 24 months, there was one regional and four distant recurrences, with no regional recurrences or differences in disease-free survival in patients treated with ALND versus PMRT + AxRT (100% vs. 98%, p = 0.67). Similarly, there were no differences in complication rates (p = 0.18).

Omitting intraoperative SLN evaluation in cT1-2N0 mastectomy patients who would be candidates for PMRT if found to have positive nodes decreased rates of ALND and minimized use of ALND + PMRT without compromising outcomes.