We aimed to explore possible drivers for urban-rural disparities in colon cancer outcomes in a single-payer health care system where all patients had access to universal health care coverage.
Patients diagnosed with stage II/III colon cancer between 2004 and 2015 in Alberta, Canada were reviewed. On the basis of postal code, patients were categorized as living in urban, rural, or suburban areas based on travel distance to the cancer center. Kaplan-Meier methods and Cox regression models assessed the associations among the area of residence, receipt of treatment, and overall survival (OS).
Of 6163 patients identified, there were 3691, 1779, and 693 from urban, rural, and suburban areas, respectively. There was a larger proportion of younger patients (P=0.033) and left-sided colon cancers (P=0.042) in urban areas. Urban patients experienced shorter times from diagnosis to surgery (P<0.001), but longer delays from surgery to adjuvant chemotherapy (P=0.001). A significant difference in outcomes was identified among urban, rural, and suburban populations where median OS were 104, 94, and 83 months, respectively (P<0.001). In multivariate analysis, the location of residence continued to predict for worse OS in suburban (hazard ratio=1.60, 95% confidence interval: 1.24-2.07, P<0.001) and rural areas (hazard ratio=1.24, 95% confidence interval: 1.02-1.50, P=0.042), when compared with urban areas.
In this population-based study, urban-rural differences in colon cancer survival persist, even in settings with universal health care coverage. These findings may be partly driven by a younger population with more left-sided colon cancers as well as expedited surgical intervention in urban populations, but these factors do not fully explain the disparities.