Are treatment disparities the missing link between institution volume, hospital teaching status and survival for women with breast cancer?

Background: Previous work has drawn links between breast cancer survival and institutional volume/hospital teaching status, but causal factors underlying these associations remain unclear. We explored the relationship between volume and teaching status with treatment patterns, in hope of revealing how these factors influence survival. Methods: Demographic, clinical and pathologic data for female breast cancer patients treated in Florida (1996-2009) were collected from the Florida Cancer Data System, Agency for Health Care Administration and Census. High-volume facilities (HVF), compared to low-volume (LVF), were defined as those treating ≥1% of patients; and teaching (TF) versus non-teaching (NTF) status was designated by 2005 AAMC. The association of facilities' volume, teaching status and receipt of treatment (surgery, radiation therapy, chemotherapy, hormone therapy) was assessed using multivariate logistic regression models. Results: Of 137,802 patients, 58.2% received care at LVF and 89.6% received care at NTF. Patients receiving care at LVF were more likely to have surgery (odds ratio [OR] 1.38 95% confidence interval [1.16-1.63]), and less likely to have chemotherapy (0.52 [0.37-0.73]) and hormone therapy (0.53 [0.36-0.78]), than their counterparts at HVF. NTF patients were also more likely to undergo surgery (1.46 [1.21-1.76]), and less likely to undergo hormone therapy (0.43 [0.26-0.73]). Radiation therapy was employed similarly for LVF/HVF and NTF/TF. Conclusion: Facility volume and teaching status influence treatment patterns for female breast cancer patients. Because LVF and NTF have previously been associated with poorer long-term survival, strategies for reducing disparities in treatments should be explored and could improve outcomes.