Background: Colorectal cancer incidence and mortality have declined with increased screening and scientific advances in treatment. However, improvement in colorectal cancer outcomes has not been equal for all groups and disparities have persisted over time.
Methods: Data from the California Cancer Registry were used to estimate changes in 5-year colorectal cancer-specific survival over three diagnostic time periods: 1997-2002, 2003-2008, and 2009-2014. Analyses included all patients in California with colorectal cancer as a first primary malignancy. Multivariable Cox proportional hazard regression models were used to evaluate the effect of race/ethnicity, insurance status, and neighborhood socioeconomic status (nSES) on 5-year colorectal cancer-specific survival.
Results: On the basis of a population-based sample of 197,060 colorectal cancer cases, racial/ethnic survival disparities decreased over time among non-Hispanic Blacks (NHB) compared with non-Hispanic Whites (NHW), after adjusting for demographic, clinical, and treatment characteristics. For cases diagnosed 1997-2002, colorectal cancer-specific hazard rates were higher for NHB [HR, 1.12; 95% confidence interval (CI), 1.06-1.19] and lower for Asians/Pacific Islanders (HR, 0.92; 95% CI, 0.87-0.96) and Hispanics (HR, 0.94; 95% CI, 0.90-0.99) compared with NHW. In 2009-2014, colorectal cancer-specific HR for NHB was not significantly different to the rate observed for NHW (HR, 1.03; 95% CI, 0.97-1.10). There were no changes in disparities in nSES, but increasing disparities by health insurance status.
Conclusions: We found a decrease in survival disparities over time by race/ethnicity, but a persistence of disparities by neighborhood socioeconomic status and health insurance status.
Impact: Further investigation into the drivers for these disparities can help direct policy and practice toward health equity for all groups.
©2020 American Association for Cancer Research.