Neoadjuvant endocrine therapy for early-stage breast cancer: An institutional experience during the COVID19 pandemic.

Abstract

e12625 Background: Neoadjuvant Endocrine therapy (NET) is under-utilized for locally advanced hormone receptor + breast cancer (BC) despite literature to date concluding that chemotherapy and NET have comparable response rates but with lower toxicity for the latter. The COVID19 pandemic presented a unique occasion to extend the use of NET for localized BC. Many surgical procedures across the country, including at Dartmouth-Hitchcock Medical Center (DHMC) were postponed in order to redirect resources. The American Society of Breast Surgeons released guidelines to manage patients in which surgery was delayed. For Estrogen Receptor + (ER+), HER2- early-stage tumors, the guidelines recommended NET as first-line treatment. Herein we review the rate of adoption of NET and patient/tumor characteristics associated with NET adoption at DHMC during the lockdown. Methods: A Retrospective analysis of patients diagnosed with early-stage ER+, HER2- BC between December 2019 and June 2020. Inclusion criteria included patients with non-metastatic hormone receptor + BC. Data extracted from chart review included age, menopausal status, tumor stage/grade, body mass index (BMI). A delay in surgery was defined as days between surgical consult and surgery over 14 days. Descriptive statistics will be applied to data collected on patient/tumor characteristics, and the number of patients accepting or declining NET. Results: 109 cases were identified within the study period with 42 cases designated as experiencing delays in surgery. The median age of the group (n = 42) was 62 and the majority was post-menopausal. 36 patients received NET with most started on an aromatase inhibitor. Median BMI was 28.5. Median duration of treatment was 39.5 days. Tumor response to NET was not clearly described in the pathology reports. Three cases were noted to have some decrease in cellularity for pathologic partial response and four had no definite response. Imaging modalities were compared to pathology size and MRI was found to be a fair predictor of size obtained from pathology specimens with a correlation metric of 0.78 indicating that it may serve as the best proxy for pre-treatment size. Pre-surgical MRIs were obtained in 51.3% of cases. The majority of patients on NET had no change in the grade of their pathology. During the course of the pandemic long-term adherence of adjuvant endocrine therapy decreased from 78% for those diagnosed in early 2020 to 56% for those diagnosed in late 2020. Conclusions: The COVID19 crisis was an unprecedented challenge to healthcare systems. Delays in surgery resulted in increased use of NET in early-stage BC. We plan to integrate other data including impact of NET on long-term adherence to endocrine therapy. Change in clinical vs pathologic stage will be reported for those with or without NET. This experience may help guide care during healthcare crises or in resources limited settings.