Abstract
BACKGROUND: The growing use of postmastectomy radiation/regional nodal irradiation (PMRT) has resulted in many women receiving both axillary dissection (ALND) and PMRT, increasing lymphedema rates. After developing standardized PMRT criteria, we adopted a policy of ALND omission among cN0 patients with 1-2 positive sentinel nodes (+SLNs) requiring PMRT. We evaluated how often overtreatment with ALND+PMRT was avoided with this approach. METHODS: A retrospective review of a prospectively maintained database was performed beginning 1 year before policy adoption. Intraoperative SLN evaluation was routine pre- and post-policy. ALND was performed for SLN macrometastasis pre-policy, and selectively performed post-policy for 1-2 +SLNs based on PMRT criteria. ALND+PMRT was required for ≥ 3 +SLNs. RESULTS: From March 1, 2018 to November 30, 2020, a total of 2207 cT1-3N0 patients had mastectomy and 231 had +SLNs; 109 (47%) were treated pre-policy and 122 (53%) post-policy. Most (81%) had 1-2 +SLNs. There was no change in rates of ALND+PMRT (64% pre-policy vs. 58% post-policy, p = 0.09), including in patients with 1-2 +SLNs (61% vs. 51%, p = 0.20). Post-policy, ALND was omitted in 9 (7%) patients recognized intraoperatively as PMRT candidates; avoidable ALND was performed in 40 (33%) patients not identified as PMRT candidates until receipt of final pathology. Overall, had intraoperative SLN evaluation been deferred, only 5.7% of patients would have required completion ALND: 2.2% (n = 49/2207) for ≥ 3 +SLNs and 3.5% (n = 77/2207) for 1-2 +SLNs without PMRT indication. CONCLUSIONS: Most patients could have avoided ALND+PMRT if decision making was deferred until final pathology was available. Selective intraoperative SLN evaluation in cN0 patients having upfront mastectomy may reduce avoidable overtreatment.