Nonadherence to Standard of Care for Locally Advanced Colon Cancer As a Contributory Factor for High Mortality Rates in Kentucky

Background: Kentucky has one of the highest mortality rates for colon cancer, despite dramatic improvements in screening. The National Comprehensive Cancer Network (NCCN) guidelines recommend operation and adjuvant chemotherapy for locally advanced (stage IIb/c and stage III) colon cancer (LACC). The purpose of this study was to determine the rate of nonadherence with current standard of care (SOC) and associated factors as possible contributors to mortality.

Methods: The Kentucky Cancer Registry database linked with administrative health claims was queried for individuals (20 years and older) diagnosed with LACC from 2007 to 2012. Bivariate and logistic regression of nonadherence was performed. Survival analysis was performed with Cox regression and Kaplan-Meier plots.

Results: A total of 1,404 patients with LACC were included. Approximately 42% of patients with LACC were noted to be nonadherent to SOC, with nearly all (95.7%) failing to receive adjuvant chemotherapy. After adjusting for all significant factors, we found the factors associated with nonadherence included the following: age older than 75 years, stage III colon cancer, high Charlson Comorbidity Index (3+), low poverty level, Medicaid coverage, and disability. Adherence to SOC is associated with a significant improvement in the 5-year survival rate compared with nonadherence (63.0% and 27.4%, respectively; p < 0.0001).

Conclusions: Our study identified multiple factors associated with the failure of patients with LACC to receive SOC, particularly adjuvant chemotherapy, suggesting the need to focus on improving adjuvant chemotherapy compliance in specific populations. Nonadherence to LACC SOC is likely a major contributor to the persistently high mortality rates in Kentucky.