Abstract PO1-17-10: Impact of COVID19 on neoadjuvant endocrine therapy use in breast cancer: A National Cancer Database analysis
Authors: Makower Della , Choi Jaeun , Fineberg Susan 
Published: May 2024

Abstract
Background: Neoadjuvant endocrine therapy (NET) is associated with similar response rates as neoadjuvant chemotherapy in hormone receptor positive (HR+) breast cancer (BC), with less toxicity. While gene expression assays such as the 21-gene recurrence score (RS) have led to decreased chemotherapy use in early HR+/HER2- BC, NET is often underutilized. In 2020, the COVID19 pandemic led to disruption in oncologic care, including cancellation of surgeries. Guidelines for BC management during the pandemic recommended NET for HR+/HER2- BC patients unable to obtain surgery due to pandemic restrictions. We evaluated NET use in 2020, compared to NET use in prior years.
Methods: Female pts with nonmetastatic HR+/HER2- BC diagnosed between 2016 and 2020 were identified from the 2004-2020 National Cancer Database (NCDB). Annual number of pts receiving NET, and duration of use, were compared between years, and characteristics of pts treated with and without NET were evaluated within and across years, using Chi-squared test for categorical variables and Wilcoxon rank-sum test or Kruskal-Wallis test for continuous variables.
Results: 554,733 pts met inclusion criteria; 84.50% white, 9.19% Black, 4.06% Asian; 5.88% Hispanic. 25,553 (4.61%) pts received NET. Annual NET use increased slightly between 2016 and 2018 [3.25% vs 3.49% (p=0.021) vs 3.89% (p &lt; 0.0001)], remained stable in 2019 (3.98%), and then increased to 8.67% in 2020 (p &lt; 0.0001). Median duration of NET remained relatively stable between 2016 and 2019 [74 days (d), 68d, 73d and 61d, 2016-2019] but declined in 2020 (56d, p&lt; 0.0001 for 2020 vs 2016, 2017, 2018, and 2019). Older age and greater comorbidities were associated with NET use in all years (p &lt; 0.0001). No racial association with NET use was seen in 2016-2018, but Black race was associated with greater NET use in 2019 (p=0.0122) and 2020 (p &lt; 0.0001). Lobular histology, moderate grade, larger tumor size, and node involvement were associated with increased NET use in all years (p &lt; 0.0001). Progesterone receptor positivity (PR+) and lower Ki67 were associated with NET use in 2020 (p=0.0007 and p&lt; 0.0001), but not prior. Median tumor size for pts receiving NET was smaller in 2020 (16mm) compared with prior years (22, 23, 22, and 21mm for 2016-2019, p&lt; 0.0001). Annual RS use increased for all pts between 2016 (34.59%) and 2020 (43.47%). RS use in NET pts was stable in 2016 (27.79%) and 2017 (27.54%), with modest increase in 2018 (29.56%; p 0.094, 2016 vs 2018, p=0.045, 2017 vs 2018), and then increased annually in 2019 (33.28%, p=0.0001) and 2020 (40.64%, p&lt; 0.0001). Median RS was higher in pts receiving NET than in pts who did not in 2016-2019 (p=0.0078, 0.0003, 0.0271, and &lt; 0.0001), but was similar in 2020 (RS=16; IQR 11, 22).
Conclusions: Frequency of NET administration more than doubled in 2020, but duration was shorter than in prior years, possibly due to use of NET as “bridging therapy” due to COVID19 restrictions. Black race was associated with receipt of NET in 2020, possibly reflecting disparate impact of COVID19 on Black communities. NET use in 2020 was also associated with smaller tumor size, lower Ki67, and greater likelihood of PR+ disease than in prior years. Use of RS to guide NET increased annually, beginning in 2018. Association of NET with older age, greater comorbidities, higher stage, moderate grade, and lobular histology were seen in all years.
Citation Format: Della Makower, Jaeun Choi, Susan Fineberg. Impact of COVID19 on neoadjuvant endocrine therapy use in breast cancer: A National Cancer Database analysis [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-17-10.