Racial differences in colorectal cancer survival linked to health at initial diagnosis

1. The initial presentation characteristics accounted for a large portion of the overall disparity in five-year survival of colorectal cancer between black and white patients.

2. This survival gap only dropped marginally after accounting for treatment differences between these patient populations.

Evidence Rating Level: 2 (Good)

Study Rundown: Colorectal cancer (CRC) accounts for 50,000 deaths in the United States annually, the second-highest among all cancers. The racial disparity in CRC survival over the last few decades has been clear, with black patients historically facing worse outcomes than white patients. To further examine the source of this disparity, this study sequentially compared one population of black patients to three paired white patient populations. Five-year survival comparisons revealed a nearly 10% difference between white and black populations, after adjusting for demographic characteristics. When the comparison was further adjusted based on health at initial diagnosis, the five-year survival difference favoring white over black patients fell by nearly one-half. After accounting for both presentation and treatment characteristics, there was still a survival disparity, suggesting that treatment regimens only account for a small portion of the differences. This study was limited in that it did not include a “hospital quality” variable in its treatment match algorithm, and it did not examine possible CRC survival disparities among other races. Still, the findings implicate health status at CRC diagnosis as a potentially major cause of racial disparities in survival.

Click to read the study today in the Annals of Internal Medicine

Relevant Reading: Racial disparities in colorectal cancer survival: To what extent are racial disparities explained by differences in treatment, tumor characteristics, or hospital characteristics?

In-Depth [retrospective cohort]: This study used patient records obtained from the Survey, Epidemiology, and End Results (SEER)-Medicare database from 1991 through 2005. The authors employed tapered multivariate matching to sequentially compare black patients with three white patient populations matched based on demographic, initial presentation (i.e., tumor stage and comorbid conditions), and treatment characteristics (i.e., chemotherapy, surgery, radiation), respectively. There was a 9.9% five-year survival difference (95%CI 8.3-11.4%, p<0.001) between white and black patients matched for demographic characteristics. A 4.9% survival difference (95%CI 3.6-6.1%, p<0.001) existed between the two patient populations after accounting for health characteristics present at initial diagnosis. However, after further adjusting the comparison based on treatment regimens, the survival difference only decreased to 4.3% (95%CI2.9-5.5%, p<0.001).

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