Overuse of Axillary Surgery in Patients with Ductal Carcinoma In Situ: Opportunity for De-escalation

Background: Ductal carcinoma in situ (DCIS) is noninvasive breast cancer and therefore nodal staging is not routinely recommended. We evaluated the use of and factors associated with axillary surgery in DCIS in the National Cancer Database (NCDB). Methods: DCIS cases were identified from the NCDB 2012–2018. Use of axillary surgery was evaluated over time, and factors associated with axillary surgery were assessed for breast-conserving surgery (BCS) and mastectomy groups. Results: We identified 178,762 patients, median age of 60 years. Majority of DCIS (87%) was ER-positive, and 14% low, 43% intermediate, and 44% high grade. Median DCIS size was 1.1 cm. BCS was performed in 72%, whereas 28% had mastectomy. Overall axillary surgery was performed in 38% and was higher in patients undergoing mastectomy compared with patients undergoing BCS (88% vs. 19%, p < 0.001). At axillary surgery, the vast majority (92%) had 1–5 nodes examined, whereas 8% had >5 nodes examined. Over time, axillary surgery decreased in BCS patients (21% in 2012 to 17% in 2018, p < 0.001) but increased slightly in mastectomy patients (86% in 2012 to 90% in 2018, p < 0.001). On multivariable analysis, factors significantly associated with axillary surgery were younger patient age, larger tumor size, higher grade, and ER-negative status. Conclusions: Factors associated with axillary surgery reflect higher risk disease for upstage to invasive cancer, indicating surgeon judgment. However, despite axillary surgery being overtreatment of DCIS, it is common in mastectomy and is performed for one in five patients undergoing BCS. This provides opportunity for improvement in breast cancer care delivery.