Factors Linked to Disparities in CRC Biomarker Testing

TOPLINE:

Several factors — most notably, older age, treatment in the community setting or at East South Central facilities, and a lower educational level in the area of residence — are associated with lower rates of microsatellite instability (MSI) and KRAS biomarker testing in patients with metastatic colorectal cancer (CRC), a recent analysis suggested.

METHODOLOGY:

• Data indicate that access to genetic testing and counseling for patients with CRC varies, but few studies have evaluated discrepancies across the United States.
• Researchers analyzed data on disparate biomarker testing and its association with clinical outcomes on a national scale in 41,061 patients with metastatic CRC, diagnosed between 2010 and 2017.
• Data were obtained from the National Cancer Database, a hospital-based cancer registry in the United States, and the study was conducted between November 2022 and March 2024.
• Patients were classified based on whether they completed MSI or KRAS testing, with sociodemographic factors such as age, race, ethnicity, educational level, median household income, insurance type, area of residence, facility type, and facility location evaluated.
• In the population (mean age, 62.3 years), 17.3% identified as Black, 78% as White, and 4.7% as other; 85% lived in a metropolitan setting, and 40.5% received treatment at a comprehensive community cancer program.

TAKEAWAY:

• In the overall cohort, only 28.8% of patients underwent KRAS testing, and 43.7% underwent MSI testing.
• Factors associated with a lower likelihood of MSI testing included older age, with the 70-79 age group having the lowest odds than with the 18-49-year group (relative risk [RR], 0.70), treatment at a community (vs an academic) cancer center (RR, 0.74), living in a rural (vs metropolitan) area (RR, 0.80), lower educational level in the area of residence (RR, 0.84), and treatment at East South Central facilities vs those in New England (RR, 0.67).
• Similar factors were linked to lower levels of KRAS testing: Older age, most notably the 70-79 age group (RR, 0.81), living in an area with lower educational level (RR, 0.92), as well as treatment at a community cancer center (RR, 0.92) or at East South Central facilities (RR, 0.78). Patients with Medicaid vs private insurance also had a lower likelihood of receiving KRAS testing (RR, 0.94).
• The survival analysis revealed that, compared with no testing, MSI and KRAS testing were associated with modest improvements in overall survival, after adjusting for cofounders (hazard ratio [HR] with MSI, 0.93; P KRAS, 0.97; P = .03).

IN PRACTICE:

“In this cohort study of patients with [metastatic] CRC, older age, lower educational level in area of residence, community-setting treatment, and treatment at East South Central facilities were associated with a lower likelihood of MSI and KRAS testing,” the authors wrote. “By highlighting the sociodemographic-based disparities in biomarker testing using national registries, we can develop strategies for promoting equity in cancer care and improving outcomes for underserved populations.”

SOURCE:

The study was led by Saad Sabbagh, MD, Cleveland Clinic Florida in Weston, Florida. It was published online on July 5 in JAMA Network Open.

LIMITATIONS:

The study’s retrospective nature did not account for nonobservable confounding variables. Data were extrapolated from the National Cancer Database, limiting the ability to report the specific timing of testing and the type of test used. The National Cancer Database does not report patients who did not undergo the test after 2017, restricting the inclusion of patients with recent years of diagnosis.

DISCLOSURES:

Steven D. Wexner, MD, reported receiving personal fees from several companies, including Baxter, Becton, Dickinson and Company, GL Supply, Glaxosmithkline, Medtronic, Olympus, and Takeda, and serving as chair of the Data Safety Monitoring Board of JSR/WCG/ACI, Polypoid, and Boomerang outside of the submitted manuscript. Additional disclosures are noted in the original article.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.