Tracking Utilization of Neoadjuvant Endocrine Therapy (NET) and Neoadjuvant Chemotherapy (NCT) for Hormone Receptor-Positive Breast Cancer (HR + BC) in the U.S.A. Over Time – A TriNetX Database Study

Purpose Hormone receptor-positive breast cancer (HR + BC) responds well to neoadjuvant endocrine therapy (NET), increasing chances for breast conserving surgery with less toxicity than neoadjuvant chemotherapy (NCT). A National Cancer Database study found that NET use increased by only 0.5% between 2004 and 2012. We investigated the utilization of NET, NCT, and no neoadjuvant therapy (no NT) from 2005 to 2023. Methods We queried the TriNetX database for patients with HR + BC (stages I-III, ER+, PR+, ERBB2-) who underwent mastectomies in the US and evaluated utilization of NET, NCT, or no NT. We trended each use by all ages, age ≤ 50 years, or ≥ 51 years across roughly 5-year increments. NET cases were less than 10 for 2005-2009, and rounding obscured the exact count, so this period was excluded from the trend analysis. Results The use of NET remained below 1%, while NCT utilization was approximately 11%, and breast conserving surgery was achieved more frequently with NET than NCT (p < .0001). Both therapy types were used more frequently with advanced cancer stage (p < .0001), and NCT use was higher than NET in both age groups (p < .0001). NET and NCT use did not show significant trends when all ages were combined (p = .39). However, age-stratified analyses revealed significant declines in NCT use within each age group, with similar NET patterns and increasing no NT (p < .0001), indicating that overall results may mask weighted subgroup trends. Conclusions This study highlights underutilization of NET, despite its low toxicity and efficacy in improving patient outcomes. Increased efforts are needed to address this gap and consider NET as an option for HR + BC.