Breast Surgical Oncology Fellow Memorial Sloan Kettering Cancer Center New York, New York, United States
Disclosure: I do not have any relevant financial / non-financial relationships with any proprietary interests.
Participants should be aware of the following financial/non-financial relationships:
Austin D. Williams, MD MSEd: I do not have any relevant financial / non-financial relationships with any proprietary interests.
Introduction: The growing use of postmastectomy radiation with regional nodal irradiation (PMRT) has resulted in many women receiving both axillary dissection (ALND) and PMRT, increasing rates of lymphedema. We developed an algorithm based upon age, number of positive sentinel nodes (+SLNs) and histologic features to identify patients requiring PMRT. We sought to examine how often overtreatment with ALND+PMRT was avoided with this approach.
Methods: In 4/2019 we adopted a multidisciplinary policy for PMRT for cN0 patients with 1-2 +SLNs, permitting ALND omission when the need for PMRT was evident intraoperatively. ALND+PMRT was indicated for ≥3 +SLNs. Intraoperative SLN evaluation was routine throughout the study period. ALND was performed for any SLN macrometastasis pre-policy, and selectively performed post-policy. ALND+PMRT rates were compared pre- and post-policy.
Results: From 3/2018-12/2020, 231 cT1-3N0 patients had mastectomy and +SLNs; 109 (47%) were treated pre- and 122 (53%) post-policy. Clinicopathologic features were similar between groups (Table). Most patients (81%) had 1-2 +SLNs, while 19% had ≥3 +SLNs. Overall, 141 (61%) patients underwent ALND+PMRT, of whom 47 (33%) met criteria for avoidance of ALND. There was no difference pre- and post-policy in the use of ALND+PMRT (64% pre vs 58% post, p=0.09), and the proportion in whom this was avoidable (34% pre vs 32% post, p >0.9). Post-policy, ALND was omitted in 17 (14%) patients recognized intraoperatively as PMRT candidates, but avoidable ALND was performed in 31 (25%) patients not identified as PMRT candidates until receipt of final pathology. Considering the entire group, if intraoperative SLN evaluation was deferred, based on final pathology, completion ALND would have been required for 44 (19%) patients for ≥3 +SLNs and 73 (32%) for 1-2 +SLNs without PMRT indication, but 114 (49%) would have been spared ALND.
Conclusions: Based on PMRT guidelines, most patients could have avoided ALND+PMRT had additional pathologic data been known. Selective use of intraoperative SLN evaluation in cN0 patients having upfront mastectomy may reduce avoidable overtreatment.
Learning Objectives:
Upon completion, participant will be able to articulate the morbidity associated with dual axillary dissection plus postmastectomy radiation and regional nodal irradiation.
Upon completion, participant will be able to describe pathologic factors used in determining the use of postmastectomy radiation and regional nodal irradiation.
Upon completion, participant will be able to understand the impact of omitting intraoperative sentinel node evaluation may have on reducing axillary overtreatment.