The Impact of Facility Volume on Rates of Pathologic Complete Response to Neoadjuvant Chemotherapy Used in Breast Cancer

Background: Patient and tumor factors have been associated with rates for pathologic complete response (pCR) to neoadjuvant chemotherapy (NAC) for breast cancer, but variation in pCR rates across facilities has not been studied. Methods: This study used the National Cancer Data Base to identify women with clinical stages 1–3a breast cancer undergoing NAC from 2010 to 2013. Generalized estimation equation models were used to examine the relationship between facility characteristics and pCR rates, with adjustment for patient and tumor factors, while accounting for patient clustering at facilities. Analyses were stratified by tumor molecular subtype. Results: Overall, 16,885 women underwent NAC, of whom 3130 (18.5%) were hormone receptor-positive (HR⁺) and human epidermal growth factor 2-positive (HER2⁺), 7045 (41.7%) were HR⁺HER2⁻, 1847 (10.9%) were HR⁻HER2⁺, and 4863 (28.8%) were HR⁻HER2⁻. Overall, 4002 of the patients (23.7%) achieved a pCR. The pCR rates were 29.5% for HR⁺HER2⁺, 10.8% for HR⁺HER2⁻, 45.3% for HR⁻HER2⁺, and 30.5% for HR⁻HER2⁻ tumors. Multivariable analysis showed that pCR rates were significantly higher at high-volume facilities (>75th vs. <25th percentile) for all tumor subtypes except HR⁺HER2⁻ tumors. Facility location and type were not significant. Adjustment for time from NAC to surgery decreased the likelihood of a pCR in high- versus low-volume facilities, but facility volume remained significantly associated with pCR. Conclusion: Facility volume, not location or type, was significantly associated with higher pCR rates in this exploratory analysis. Time to surgery has a modest impact on pCR rates across facilities, but further study to identify other potentially modifiable factors is needed.