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-S 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.