Beyond the physician shortage: infrastructure as a rate-limiting step in breast cancer care.

Background: Breast cancer is the most common cancer among women in the United States, yet early detection and survival vary widely across regions. Physician shortages and limited facility access are both implicated, but whether local infrastructure modifies the association between physician workforce availability and breast cancer outcomes remains uncertain. Clarifying this relationship is critical to guide policy and investment. Study design: This county-level cross-sectional study used data from the Area Health Resource File, Behavioral Risk Factor Surveillance System, and Centers for Disease Control and Prevention. Provider density was defined as the number of primary care physicians and obstetrician-gynecologists (screening) or surgeons and radiation oncologists (treatment) per 100, 000 women aged 50-74. Facility availability was defined as the presence of mammography services (screening) and surgical and chemotherapy services (treatment). A neighboring-county facility index estimated regional access. Outcomes were county-level screening rates, late-stage diagnoses, and mortality. Adjusted generalized linear models with provider density-by-facility availability interaction terms estimated whether the association between provider density and breast cancer outcomes in women aged 50-74 differed according to local facility availability. Results: High-density counties were more likely to be urban, socioeconomically advantaged, and have mammography facilities (p<0.001). In adjusted models, greater provider density was associated with increased screening (β=1.49, p<0.001) and decreased late-stage diagnosis (β=-1.29, p<0.001) and mortality (β=-1.09, p<0.001), but only when facilities were available. Among counties lacking local facilities, more neighboring counties with screening or treatment resources was associated with higher screening (β=1.23, p=0.047) and lower mortality (β=-1.69, p=0.023). Conclusions: Among women aged 50-74 years, provider density was associated with more favorable outcomes only when facilities were available, suggesting that increasing workforce availability alone may be insufficient without local healthcare infrastructure. Aligning workforce expansion with infrastructure investment may reduce disparities in breast cancer outcomes.