Regional diagnostic rates, treatments, and outcomes among patients with invasive ductal carcinoma

Background The association between regional breast cancer diagnostic rates, treatments, and outcomes is unclear. We sought to investigate the management and survival of women with invasive ductal carcinoma (IDC) from geographic regions with variable rates of diagnosis. Methods Data on women diagnosed with IDC years 2009-2010 were obtained from the Surveillance, Epidemiology, and End Results database. Patients were divided into quartiles based on the IDC diagnostic rate within their county of residence. Chi-square and one-way analysis of variance (ANOVA) analyses tested the association between patient and clinical characteristics and the diagnostic rate quartiles. Cox regression analyses compared survival between the quartiles. Results Among the 83,375 patients included, the mean age was 60.8 y and 70.9% were white. Patients residing in counties with the highest diagnostic rates were more frequently white, employed, educated, and wealthier and more often received adjuvant radiation following both partial mastectomy for localized disease and complete mastectomy for advanced disease compared to patients in counties with the lowest diagnostic rates. The highest diagnostic rate quartile had 10% decreased odds of death compared to the lower quartile (hazard ratio: 0.897; 95% confidence interval: 0.832-0.966). However, after adjustment for socioeconomic variables, survival was comparable (hazard ratio: 0.916; 95% confidence interval: 0.835-1.003). Conclusions Regional variation in IDC diagnostic rates is associated with differences in socioeconomic status, grade, stage, and treatment. Patients from regions with the highest rates of diagnosis may have improved access to evidence-based care and resultant superior survival. Enhancing access to care may improve outcomes of patients residing in regions where breast cancer is diagnosed less frequently.