ASO Visual Abstract: Nodal Surgery for Patients ≥70 Undergoing Mastectomy for DCIS? Choose Wisely

Background Routine sentinel lymphadenectomy (SLNB) for early-stage HR+/HER2- breast cancer in women >= 70 is discouraged by Choosing Wisely, but whether SLNB can be routinely omitted in women >= 70 with DCIS undergoing mastectomy is unclear. This study aims to evaluate rates of axillary surgery and nodal positivity (pN+) in this population to determine the impact of axillary surgery on treatment decisions. Methods Females >= 70 with DCIS undergoing mastectomy were identified from the National Cancer Database (2012-2020). The rate of upstaging to invasive cancer (>= pT1) or pN+ was assessed. Subset analyses were conducted for ER+ patients. Adjuvant therapies were evaluated among >= pT1 patients after stratifying by nodal status. Results Of 9,030 patients, 1,896 (21%) upstaged to >= pT1. Axillary surgery was performed in 86% of patients, predominantly sentinel lymphadenectomy (SLNB, 65%). Post hoc application of Choosing Wisely criteria demonstrated that 93% of the entire cohort and 97% of ER+ DCIS patients could have avoided axillary surgery. Nodal positivity was 0.3% among those who didn't upstage, and 12% among those upstaging to >= pT1, with <2% having pN2-3 disease, irrespective of receptor subtype. Node-positive patients had higher adjuvant therapy usage, but there was no recommendation for adjuvant chemotherapy or radiation for 71% and 66% of pN+ patients, respectively. Conclusions Axillary surgery can be omitted for most patients >= 70 undergoing mastectomy for ER+ DCIS, aligning with recommendations for invasive cancer, and omission can be considered in those with ER- disease. Future guidelines incorporating preoperative imaging, as in the SOUND trial, may aid in identifying patients benefiting from axillary surgery.