Impact of hospital volume on mortality in adult women over 65 with triple-negative breast cancer

INTRODUCTION: Older adults (≥65 years) with triple-negative breast cancer (TNBC) have higher mortality rates than younger patients, due in part to greater comorbidity and lower rates of treatment. However, the impact of hospital volume on survival outcomes in this population remains understudied. This study examined the relationship between hospital volume and survival among older adults (aged 65 years or older) diagnosed with TNBC. MATERIALS AND METHODS: The National Cancer Database was queried for women ages ≥65 years with stage I-III TNBC diagnosed between 2010 and 2020. Annual hospital volume was the facility-level average of breast cancer cases treated in the years before the year of diagnosis. Volumes were divided into quartiles, with the lowest quartile (≤136 cases/year) defined as low-volume and the remaining three quartiles combined as high-volume. Sociodemographic, clinical, and treatment characteristics were compared according to hospital volume status. Crude and adjusted mortality risk differences and relative risks were estimated using pooled logistic regression models. RESULTS: The study cohort comprised 37,538 older women with TNBC, of whom 25 % (n = 9388) were treated at low-volume hospitals. Patients treated at low-volume hospitals were slightly older (73 years [IQR: 68 to 79] vs. 72 years [IQR: 68 to 78 years]) and traveled a shorter distance to the hospitals (6.80 miles [IQR: 3.00 to 14.30] vs 8.60 miles [IQR: 4.30 to 18.00]) than those treated at high-volume hospitals (p < 0.001). On adjusted analysis, treatment at low-volume hospitals (Low-Value Risk: 0.607, 95 % CI: 0.579 to 0.638) was associated with a 5.5 % increased risk of all-cause mortality compared to treatment at high-volume hospitals (High-Volume Risk: 0.576, 95 % CI: 0.556 to 0.592) (RR: 1.055, 95 % CI: 1.003 to 1.121). Patients treated at low-volume hospitals had a 3.2 % excess adjusted risk of mortality compared to those treated at higher-volume hospitals (RD: 3.2 %, 95 % CI: 0.2 % to 6.9 %). DISCUSSION: Older adults treated at low-volume hospitals had modestly higher mortality than those at high-volume facilities. Future work should identify mechanisms underlying this relationship and assess whether referral patterns for older adults should consider hospital volume.