Effectiveness of a Short Duration of Neoadjuvant Endocrine Therapy in Patients with HR+ Breast Cancer—An NCDB Analysis (2004–2016)

Background: National medical/surgical organizations have recommended the use of neoadjuvant endocrine therapy (NET) to bridge surgery delay of weeks to months for patients with hormone receptor positive (HR+) breast cancer during the ongoing coronavirus disease 2019 (COVID-19) pandemic. The effects of NET of varying durations on pathologic response are unclear. Using the National Cancer Database (NCDB), we evaluated objective response to short (< 9 weeks), moderate (9–27 weeks), and long (> 27 weeks) duration of NET. Patients and Methods: The study cohort included female patients diagnosed with nonmetastatic invasive HR+ breast cancer, stratifying by those who received NET versus no NET between 2004 and 2016. Pathologic response was grouped into four categories (complete, downstaged, stable, upstaged) by comparing clinical and pathologic staging data. Objective response to NET included complete, downstaged, and stable pathologic response. Clinical characteristics were compared using χ² and analysis of variance (ANOVA) tests. Multivariable logistic regression was used to determine factors associated with NET use and objective response according to NET duration. Results: A minority (1.2%) received NET in our cohort. Factors associated with NET use included older age, non-Black patients, more advanced clinical stage, higher comorbidity score, government insurance, and lobular histology. Objective response rate (ORR) was 56.7%, 52.1%, and 49.0% after short, moderate, and long NET duration, respectively. Conclusion: Short NET duration did not result in an inferior ORR. Future study to evaluate the interaction between surgery delay and NET use on clinical outcome will provide insights into the safety of NET to bridge potential surgery delay in patients with HR+ breast cancer.