Effects of Cancer Stage and Treatment Differences on Racial Disparities in Survival From Colon Cancer: A United States Population-Based Study

Abstract

Background & Aims We evaluated differences in treatment of black vs white patients with colon cancer and assessed their effects on survival, based on cancer stage. Methods We collected data from the Surveillance, Epidemiology and End Results (SEER)-Medicare database and identified 6190 black and 61,951 white patients with colon cancer diagnosed from 1998 through 2009 and followed through 2011. Three sets of 6190 white patients were sequentially matched, using a minimum distance strategy, to the same set of 6190 black patients based on demographic (age, sex, diagnosis year, and SEER registry), tumor presentation (demographic plus comorbidities, tumor stage, grade, and size), and treatment (presentation plus therapies) variables. We conducted sensitivity analyses to explore the effects of socioeconomic status in a sub-cohort that included 2000 randomly selected black patients. Racial differences in treatment were assessed using a logistic regression model; their effects on racial survival disparity were evaluated using Kaplan-Meier method and Cox proportional hazards model. Results After patients were matched for demographic variables, the absolute 5 y difference in survival between black and white patients was 8.3% (white, 59.2% 5 y survival; blacks, 50.9% 5 y survival) (P<.0001); this value decreased significantly, to 5.0% (P<.0001), after patients were matched for tumor presentation, and decreased to 4.9% (P<.0001) when patients were matched for treatment. Differences in treatment therefore accounted for 0.1% of the 8.3% difference in survival between black and white patients. After patients were matched for tumor presentation, racial disparities were observed in almost all types of treatment; the disparities were most prominent for patients with advanced-stage cancer (stages III or IV, up to 11.1% difference) vs early-stage cancer (stages I or II, up to 4.3% difference). After patients were matched for treatment, there was a greater reduction in disparity for black vs white patients with advanced-stage compared with early-stage cancer. In sensitivity analyses, the 5 y racial survival disparity was 7.7% after demographic match, which was less than 8.3% observed in the complete cohort. This reduction was likely due to the differences between the sub-cohort and the complete cohort in those variables that were not included in the demographic match. This value was reduced to 6.5% (P=.0001) after socioeconomic status was included in the demographic match. The difference decreased significantly to 2.8% (P=.090) after tumor presentation match, but was not further reduced after treatment match. Conclusions We observed significant disparities in treatment and survival of black vs white patients with colon cancer. The disparity in survival appears to have been more strongly affected by tumor presentation at diagnosis than treatment. The effects of treatment differences on disparities in survival were greater for patients with advanced-stage, vs early-stage, cancer.

Colorectal cancer statistics, 2017

“…Although black patients are less likely than others to receive appropriate surgery, adjuvant chemotherapy, and radiation treatments, survival is lower in black than in white patients even when treatment is equal . A recent study found that tumor presentation at diagnosis played a larger role in survival differences than treatment, estimating that 40% of the racial disparity in colon cancer survival is because of the combined effects of later stage at diagnosis, a higher likelihood of unfavorable tumor characteristics, and more comorbidities among black patients . Survival disparities are also evident within racial and ethnic groups.…”

“…50 A recent study found that tumor presentation at diagnosis played a larger role in survival differences than treatment, estimating that 40% of the racial disparity in colon cancer survival is because of the combined effects of later stage at diagnosis, a higher likelihood of unfavorable tumor characteristics, and more comorbidities among black patients. 51 Survival disparities are also evident within racial and ethnic groups. For example, blacks who are privately insured are 46% more likely…”

Cancer statistics for African Americans, 2019

“…). Racial disparities in CRC survival largely reflect differences in treatment, SES, comorbidities, and tumor characteristics . Numerous studies have documented that blacks with CRC are less likely than whites to receive recommended surgical treatment, radiation, and chemotherapy .…”

Recent insights into nanotechnology development for detection and treatment of colorectal cancer

“…Finally, stage IV colon cancer is divided into stages IVA and IVB. 10,11 Table 1 provides the descriptions of all these stages. Per recent investigations, 5-year survival rates are .90% for stage I CRC and ,10% for stage IV CRC.…”