Overall Survival Differences in Young Black Colorectal Cancer Patients: a Report from the National Cancer Database

Abstract

Objectives: Black patients have the highest overall incidence rate of early onset colorectal cancer, with many of these patients presenting with more aggressive disease at diagnosis, ultimately leading to decreased overall survival. We aimed to (1) evaluate how race and age affected overall survival in colorectal cancer patients, and (2) determine the different demographic and clinical covariables that may influence survival in younger individuals. Methods: The 2017 National Cancer Database (NCDB) was used to identify all patients that had colorectal cancer between 2004-2017. These patients were then divided into groups according to age (<45 and ≥45 years old) and race (white and black). Overall survival (OS) between white and black groups according to age was compared. Initial testing of survivor functions between groups revealed violations of the proportional hazards assumption. Accordingly, we used parametric maximum likelihood analyses fitting the survivor functions to Weibull distributions. Logistic regression analysis was used to determine univariate and multivariate relationships between the covariates and race for younger subjects. Propensity score matching analysis was also used to control for differences in the demographic or clinical variables between the young black versus white subgroups. Results: Out of 1.4 million potential cases initially identified, 207,823 unique cases were deemed eligible for evaluation based on study criteria. Black patients in the study population were more likely to be female, have medical comorbidities, and come from areas with lower average income and baseline education. OS was lower in older patients of both race categories when compared to the younger cohorts. Among patients older than 45 years, there were no significant differences in proportional hazard of death between black and white patients. However, among those younger than 45 years, younger black patients had significantly increased hazard of death. Regarding disease burden at diagnosis, pathologic characteristics and overall risk of death, there were no significant differences between black and white patients. Conclusions: Overall survival in young black patients with colorectal cancer is significantly reduced when compared to young white patients, even when controlling for demographic and pathologic factors. This suggests that the outcome disparities between black and white patients are complex, and the underlying factors are not well understood.

Keywords: colorectal cancer; racial disparities; young onset.

Figure 1

Consort diagram for sample sizes in each group

Figure 2

Overall survival by Kaplan-Meier analysis. (A) Overall survival was lower (p < 0.05) in both older groups compared to the race-matched younger cohorts. This finding remained true when controlling for demographic (B) or cancer staging factors (C).

Figure 3

(A) Overall survival in the younger black group was significantly lower (p < 0.05) compared to their white counterparts and remained lower when controlled for demographics (B) or cancer staging factors (C).

Figure 4

Propensity score matching analysis was performed for Social/Demographic factors (Sex, Comorbidities, Income, and Education) and cancer staging factors (Clinical stage, Lymphovascular invasion, and Grade) to achieve a 1:1 match using the nearest neighbor algorithm. A concordant group of young white subjects was identified for each of the analyses, giving a final sample size of 2,255 for each of the groups. (A) Results of propensity scores for matching on social/demographic factors. (B) Kaplan-Meier analysis revealed significantly lower survival (log-rank test) in the young black group compared to the young white group (p<0.05). (C) Propensity scores for matching on cancer staging factors. (B) Kaplan-Meier analysis revealed significantly lower survival (log-rank test) in the young black group compared to the young white group (p<0.05).