Racial disparity in consultation, treatment, and the impact on survival in metastatic colorectal cancer.
BACKGROUND
Black patients with metastatic colorectal cancer have inferior survival compared to white patients. The purpose of this study was to examine disparity in specialist consultation and multimodality treatment and the impact that treatment inequality has on survival.


METHODS
We identified 9935 non-Hispanic white and 1281 black patients with stage IV colorectal cancer aged 66 years and older from the Surveillance, Epidemiology, and End Results (SEER)-Medicare linked database. Logistic regression models identified race-based differences in consultation rates and subsequent treatment with surgery, chemotherapy, or radiation. Multivariable Cox regression models identified potential factors that explain race-based survival differences. All statistical tests were two-sided.


RESULTS
Black patients had lower rates of consultation with surgery, medical oncology, and radiation oncology. Among patients seen in consultation, black patients received less surgery directed at the primary tumor, liver- or lung-directed surgery, chemotherapy, and radiotherapy. Unadjusted survival analysis found a 15% higher chance of dying for black patients compared with white patients (hazard ratio [HR] = 1.15; 95% confidence interval (CI) = 1.08 to 1.22; P < .001). Adjustment for patient, tumor, and demographic variables marginally reduced the risk of death (HR = 1.08; 95% CI = 1.01 to 1.15; P = .03). After adjustment for differences in treatment, the increased risk of death for black patients disappeared.


CONCLUSIONS
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.
Affiliations of authors: Center for Advanced Radiotherapy Technologies, Department of Radiation Medicine and Applied Science (DRS, JHG, LKM, JDM), Department of Family & Preventive Medicine (MEM), Division of Gastroenterology, Department of Internal Medicine (SG), Division of Hematology-Oncology (GH, PF), Department of Surgery (SR), Moores Cancer Center (DRS, MEM, SG, JHG, LKM, GH, PF, SR, JDM), University of California San Diego, La Jolla, California; San Diego Veterans Affairs Healthcare System, San Diego, California (SG); Department of Radiation Oncology, Stanford University, Stanford, California (QL).
Daniel R
DR
Simpson
María Elena
ME
Martínez
Samir
S
Gupta
Jona
J
Hattangadi-Gluth
Loren K
LK
Mell
Gregory
G
Heestand
Paul
P
Fanta
Sonia
S
Ramamoorthy
Quynh-Thu
QT
Le
James D
JD
Murphy
D001741:Black or African American / Q000706:statistics & numerical data*; D000368:Aged; D000369:Aged, 80 and over; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D017024:Chemotherapy, Adjuvant / Q000706:statistics & numerical data; D015179:Colorectal Neoplasms / Q000401:mortality* / Q000473:pathology / Q000628:therapy*; D003131:Combined Modality Therapy / Q000706:statistics & numerical data*; D005260:Female; D054625:Healthcare Disparities / Q000706:statistics & numerical data*; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008495:Medical Oncology / Q000706:statistics & numerical data; D008498:Medical Record Linkage; D006278:Medicare; D009367:Neoplasm Staging; D018714:Radiotherapy, Adjuvant / Q000706:statistics & numerical data; D012017:Referral and Consultation / Q000706:statistics & numerical data*; D018426:SEER Program; D016896:Treatment Outcome; D014481:United States / Q000453:epidemiology; D044465:White People / Q000706:statistics & numerical data*