Abstract P2-15-03: Neoadjuvant endocrine therapy (NET) as bridge therapy for early stage breast cancer during COVID-19: A single institution experience

Abstract Background: Neoadjuvant endocrine therapy (NET) has long been limited to patients who were deemed medically unfit for immediate surgery or on clinical trials. Coronavirus disease 2019 (COVID-19) resulted in a global pandemic, which led to deferral of elective surgeries including breast surgeries for early stage breast cancer patients during March - June 2020. Institutional guidelines were developed based on societal recommendations, including NCCN, to use NET as a bridge to surgery. Objective: Primary objective was to establish a database of early stage HR+ Her2/neu- breast cancer patients diagnosed during COVID-19 who were treated with NET as a bridge to surgery. Secondary endpoints include correlation between duration of NET and changes in pathological variables. Method: This was a single institution, retrospective observational study from Perlmutter Cancer Center at NYU Langone Hospital and NYU Langone Hospital - Long Island of DCIS and early stage breast cancer patients diagnosed from March 15, 2020 - June 1, 2020 during COVID-19 pandemic. Inclusion criteria were males and females older than 18 years of age and initial diagnosis of DCIS or early stage HR+ Her2/neu- breast cancer who did not require neoadjuvant chemotherapy by established guidelines. Descriptive statistics were calculated separately by DCIS and invasive breast cancer using SAS version 9.4. Results: From March 15 - June 1, 2020, 13 patients who were diagnosed with DCIS and 41 patients with early stage HR+ Her2/neu- invasive breast cancer received NET (Table 1). Of the 41 patients with invasive breast cancer, 19 (46%) had Oncotype DX assay on biopsy specimens; 12/19 (63%) had scores 10-14 and 7/19 (37%) had scores 15-25. 38/41 (92.7%) had post-surgery Ki-67% and 16/38 (42.1%) demonstrated maturation arrest (Ki-67 <2.7%). 26/41 (63%) invasive breast cancer patients had pre and post Ki-67% checked while on aromatase inhibitors (AI); 21/26 (81%) had a decrease in Ki-67%, 2/26 (7.7%) patients had no change, and 3/26 (11.5%) had an increase. Of those 21 patients, the percent change of Ki-67% from baseline was mean 69.15% ± 22.58 and median 71.83%. No significant associations with changes (pre to post) in Ki-67%, T stage, ER% and PR% in NET for ≤4 weeks and >4 weeks (Table 2). Median duration of NET in invasive breast cancer was 6.85 weeks. 1 patient had a complete pathological response after NET and 2 patients were upstaged from DCIS to invasive carcinoma at the time of surgery. Conclusion: While the sample sizes are small, this is a unique cohort of early stage surgically resectable breast cancer patients who were treated with NET during the COVID-19 pandemic. This real-world data confirms pathological changes, especially decrease in Ki-67% even with short duration use of NET that has been reported in trials of neoadjuvant AI. Long term follow-up for survival outcome is planned. Table 1.Demographics of early stage breast cancer patients diagnosed during COVID-19.DCIS (n=13)Invasive Breast Cancer (n=41)Total (n=54)Menopause status (n, %)Pre-menopause7 (53.8)6 (14.6)13 (24.1)Post-menopause6 (46.2)35 (85.4)41 (75.9)Diagnosis (n, %)Self-Palpated08 (19.5)8 (14.8)Screening13 (100)33 (80.5)46 (85.2)Age (n, %)≤503 (23.1)5 (12.2)8 (14.8)50+10 (76.9)36 (87.8)46 (85.2)Clinical Stage (n, %)Tis13 (100)013 (24.1)I037 (90.2)37 (68.5)II04 (9.8)4 (7.4)NET in weeks (n, %)≤43 (23.1)11 (26.8)14 (25.9)4+10 (76.9)30 (73.2)40 (74.1)Genomic Testing (n, %)Oncotype DX019 (86.4)19 (86.4)ProSigna03 (13.6)3 (13.6)Mammaprint000 Table 2.No significant associations with changes in pre to post in T stage, ER%, PR% or Ki-67% in patients treated with NET for ≤4 weeks and >4 weeks.≤4 weeks>4 weeksp-valueChange in T stage0.5810Decrease2 (27.27%)8 (26.67%)No change7 (63.64%)15 (50%)Increase1 (9.09%)7 (23.33%)Change in ER%0.2444Decrease4 (36.36%)9 (30%)No change4 (36.36%)5 (16.67%)Increase3 (27.27%)16 (53.33%)Change in PR%1.0000Decrease7 (70%)21 (70%)No change2 (20%)5 (16.67%)Increase1 (10%)4 (13.33%)Change in Ki-67%0.3224Decrease4 (66.67%)17 (85%)No Change1 (16.67%)1 (5%)Increase1 (16.67%)2 (10%) Citation Format: Julie Huang, Joshua Feinberg, Bahram Dabiri, Jordan Baum, Meredith Akerman, Anthony Pasquarella, Abhinav Rohatgi, Shubhada Dhage, Amber Guth, Nina D'Abreo. Neoadjuvant endocrine therapy (NET) as bridge therapy for early stage breast cancer during COVID-19: A single institution experience [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P2-15-03.