Clinical Impact of Semi-Annual Mammography in Patients Undergoing Breast Conserving Surgery Following Neoadjuvant Therapy

Introduction Guidelines recommend annual mammography for most patients following breast conserving surgery (BCS) for invasive breast cancer (IBC). However, for patients treated with BCS following neoadjuvant therapy (NAT), the optimal frequency for surveillance has not been established. The study objective is to assess the efficacy of semi-annual mammography after BCS in patients treated with NAT. Methods An institutional database of patients with IBC (cT1-T4, N0-N3, M0) who received BCS following NAT from 2007-2020 was analyzed. Clinicopathologic features, surveillance imaging, and outcomes were analyzed. Direct costs associated with surveillance were estimated based on Medicare Physician Fees. Results 139 patients received BCS following NAT, of which 59 (42.4%) had a pathologic complete response. Most patients received semi-annual mammography for 24 months post-operatively (84.2%, 82.0%, 80.0%, and 78.0% of patients received a mammogram at 6, 12, 18, and 24 months, respectively). Biopsies were performed due to abnormal imaging findings in 9 (6.5%), 7 (5.3%), 2 (1.5%), and 8 (6.3%) patients at 6, 12, 18, and 24 months, respectively. Overall, 77.8% of biopsies performed were benign. At median follow up of 65 months (IQR 37-86), 22 (15.8%) patients developed recurrences, of which 14 (63.6%) were distant and 8 (36.4%) were locoregional. Only 2 (1.4%) patients had a recurrence detected by mammographic surveillance. The additional direct costs associated with semi-annual imaging was $373.68 per patient. Conclusions There is insufficient evidence to support semi-annual mammography in the early post-operative period following BCS in patients treated with NAT, and annual mammography with clinical exam is likely sufficient. Synopsis To date, there is no consensus on the optimal frequency of mammographic surveillance in breast cancer patients receiving breast conserving surgery following neoadjuvant therapy given their higher risk for recurrent disease. Our data demonstrates overall low-yield and high costs associated with semi-annual mammography and suggests that annual mammography with clinical breast exam is sufficient for detecting locoregional recurrences.