Reduced Specialist Consultation and Multimodality Therapy May Account for Poorer Survival in Black Patients With Metastatic Colorectal Cancer
Black patients with metastatic colorectal cancer have been found to have poorer survival than white patients. In a study reported in Journal of the National Cancer Institute, Simpson et al found that black patients were less likely to have specialist consultations and to receive multimodality therapy than white patients, with these disparities appearing to account for poorer survival.
Study Details
The study involved 9,935 non-Hispanic white patients and 1,281 black patients with stage IV colorectal cancer aged ≥ 66 years identified from the Surveillance, Epidemiology, and End Results (SEER)-Medicare linked database. Logistic regression models were used to identify racial differences in consultation rates and subsequent treatment with surgery, chemotherapy, or radiation, and multivariable Cox regression models were used to identify factors contributing to racial survival differences.
Overall, black patients were more likely to be younger at diagnosis, be unmarried, live in the South or Midwest, have a greater frequency of comorbid disease, have colon primary tumor, and be treated at a teaching hospital. In the entire population, 72% of patients had surgery for the primary colon or rectal tumor, 5.0% had liver or lung resection, 6.6% had surgical diversion or ostomy placement, 50% received chemotherapy, and 13% received radiotherapy. Female patients accounted for 53% of white patients and 56% of black patients.
Differences in Specialist Consultation and Treatment
On multivariate analysis adjusting for age at diagnosis, sex, Charlson comorbidity score, tumor site, primary tumor size, tumor grade, geographic region, income level, urban/rural residence, and year of diagnosis, black patients were significantly less likely to have surgery for primary tumor (59% vs 66%, adjusted odds ratio [OR] = 0.81, P = .02), liver/lung surgery (2.9% vs 4.7%, OR = 0.62, P = .01), chemotherapy (40% vs 48%, OR = 0.82, P = .005), and radiotherapy (9% vs 13%, OR = 0.75, P = .02).
On multivariate analysis, black patients were significantly less likely to have surgical consultation (88% vs 91%, OR = 0.73, P = .005) and to receive liver/lung surgery after surgical consultation (3.3% vs 5.2%, OR = 0.64, P = .02) and were significantly less likely to receive chemotherapy after consultation with a medical oncologist (50% vs 59%, OR = 0.85, P = .04). Black patients were borderline significantly less likely to have a consultation with a radiation oncologist (17% vs 22%, OR = 0.84, P = .06) and to receive radiation therapy after consultation with a radiation oncologist (55% vs 58%, OR = 0.72, P = .06).
Effect of Disparities on Survival
In unadjusted overall survival analysis, black patients had a significant 15% greater risk of death (hazard ratio [HR] = 1.15, P < .001). This increased risk remained significant after adjustment for age at diagnosis, sex, and Charlson comorbidity score (HR = 1.17, P < .001); all of the foregoing factors plus tumor site, tumor size, and histologic grade (HR = 1.15, P < .001); and all of the foregoing factors plus geographic region, income level, urban/rural, and year of diagnosis (HR = 1.08, P = .03).
After adjustment for all other factors plus the treatment factors of chemotherapy and liver/lung surgery, the difference in overall survival was no longer significant (HR = 1.01, P = .70).
The investigators concluded: “Our study shows racial disparity in specialist consultation as well as subsequent treatment with multimodality therapy for metastatic colorectal cancer, and it suggests that inferior survival for black patients may stem from this treatment disparity. Further research into the underlying causes of this inequality will improve access to treatment and survival in metastatic colorectal cancer.”
James D. Murphy, MD, of University of California, San Diego, is the corresponding author for the Journal of the National Cancer Institute article.
The study was supported by grants from the American Society of Clinical Oncology and Varian Medical Systems.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
