Objective: We examined the extent of changes in absolute and relative geographic disparities in six colorectal cancer (CRC) indicators using data about persons aged 50 and older from 195 counties in the 1988-2006 Surveillance, Epidemiology, and End Results Program database.
Methods: County-level trends in six colorectal cancer indicators (overall CRC incidence, descending colon cancer incidence, proximal colon cancer incidence, late-stage CRC incidence, CRC mortality, and 5-year probability of CRC death) were summarized using the estimated annual percentage change. Observed county rates were smoothed using Bayesian hierarchical spatiotemporal methods to calculate measures of absolute and relative geographic disparity and their changes over time.
Results: During the study period, absolute disparity for all six indicators decreased (CRC incidence: 43.2%; proximal colon cancer: 31.9%; descending colon cancer: 52.8%; late-stage CRC: 50.0%; CRC mortality: 57.8%; 5-year CRC-specific probability of death: 12.2%). Relative disparity remained stable for all six indicators over the entire study period.
Conclusion: Important progress has been made toward achieving the Healthy People 2010 and NCI strategic objectives for reducing geographic disparities, although absolute and relative disparities remain in CRC.