Racial Disparities and Standard Treatment in Locally Advanced Rectal Cancer: a National Cancer Database Study

Background:Mortality rates in colorectal cancer (CRC) continue to be higher in Black compared to White patients. While standard treatment modalities for locally advanced rectal cancer have been shown to improve outcomes, there are limited studies assessing the receipt of standard treatment in rectal cancer based on race. Therefore, we sought to evaluate the use of standard treatment across racial groups in locally advanced rectal cancer and its effect on survival. Methods:The National Cancer Database (NCDB) was queried for patients ≥18 years old with clinical and pathologic stage II-III rectal adenocarcinoma who received treatment from 2004 to 2014. Standard treatment was defined as complete surgical excision with either neoadjuvant or adjuvant concurrent chemoradiation. Multivariable logistic regressions were used to identify racial differences in receiving standard treatment. Cox proportional hazards were used to estimate the effects of standard vs. nonstandard treatment on survival differences based on race. Results:A total of 70,677 patients with stage II (n=35,079) or stage III (n=35,598) rectal adenocarcinoma met the inclusion criteria. On multivariate analysis, Black [odds ratio (OR): 0.75; 95% confidence interval (CI): 0.71-0.79; P<0.001] and Hispanic White (OR: 0.86; 95% CI: 0.80-0.92; P>0.001) patients were less likely to receive standard treatment compared to non-Hispanic White patients. On multivariable Cox regression, nonstandard treatment was significantly associated with worse survival [hazard ratio (HR): 1.69; 95% CI: 1.65-1.73; P<0.001] compared to standard treatment. Even after adjusting for patient, demographic, and facility characteristics, Black patients had higher mortality rates compared to White patients in the whole population (HR: 1.15; 95% CI: 1.09-1.20; P<0.0001). This survival difference between Black and non-Hispanic White patients persisted in both the standard (HR: 1.10; 95% CI: 1.03-1.19; P=0.008) and nonstandard (HR: 1.17; 95% CI: 1.10-1.25; P<0.0001) treatment subgroups. Decreased survival outcomes in Black patients were more pronounced for those who underwent nonstandard treatment, particularly when treating stage III disease (HR: 1.30; 95% CI: 1.19-1.42; P<0.0001). Conclusions:Nonstandard treatment in stage II and III rectal cancer is associated with worse survival compared to standard treatment regimens. Black patients are more likely to receive nonstandard treatment and have worse survival outcomes compared to White patients.