Sociodemographic factors linked to likelihood of biomarker testing in colorectal cancer
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Key takeaways:
- Less than half of patients received MSI testing and about one-quarter received KRAS testing.
- Older age, rural residency and other factors appeared linked with lower likelihood of testing.
Sociodemographic factors may contribute to disparities in testing for two key biomarkers among patients with metastatic colorectal cancer, according to study results.
Variables associated with reduced likelihood of microsatellite instability (MSI) and KRAS testing included older age, lower educational levels in area of residence and treatment at community facilities.
Background, methods
Limited data exist on disparities in biomarker testing and their impact on outcomes for patients with metastatic colorectal cancer, according to study background.
Saad Sabbagh, MD, resident physician in internal medicine at Cleveland Clinic Florida, and colleagues conducted a retrospective cohort study to evaluate socioeconomic and demographic inequities in MSI and KRAS biomarker testing and assess the impact on OS.
Researchers used the National Cancer Database to identify 41,061 patients (54.5% men; mean age, 62.3 years; 78% white) diagnosed with metastatic colorectal cancer between 2010 and 2017.
A considerable percentage of the cohort had Medicare insurance (43.6%), underwent treatment at a comprehensive community cancer program (40.5%) and lived in an area with a lower educational level (51.3%).
Investigators assessed whether patients completed MSI or KRAS tests. They evaluated test completion based on socioeconomic or demographic factors, including race, age, ethnicity, median household income, educational level in the area of residence, insurance type, and facility type and location.
Researchers also evaluated OS.
Results, next steps
Fewer than half (43.7%) of patients underwent MSI testing, and about one-quarter (28.8%) underwent KRAS testing.
Results revealed several factors associated with reduced likelihood of MSI testing, including older age. Compared with patients aged 18 to 49 years, results showed lower testing likelihood among those aged 70 to 79 years (RR = 0.7; 95% CI, 0.66-0.74), those aged 60 to 69 years (RR = 0.75; 95% CI, 0.72-0.78 and those aged 50 to 59 years (RR = 0.84; 95% CI, 0.81-0.87).
Receiving treatment at a community cancer center (RR = 0.74; 95% CI, 0.7-0.79), rural residence (RR = 0.8; 95% CI, 0.69-0.92) and living in an area of lower educational level (RR = 0.84; 95% CI, 0.79-0.89). Rates also varied by treatment location.
Researchers observed similar patterns with KRAS testing.
Patients aged 70 to 79 years had the lowest likelihood of KRAS testing compared with those aged 18 to 49 years (RR = 0.81; 95% CI, 0.78-0.84).
Residency in an area where a higher percentage of adults had no high school diploma, treatment at a community center program vs. an academic center program, and Medicaid insurance vs. private insurance also appeared significantly associated with lower KRAS testing rates.
Multivariable analyses showed modest OS improvements among patients who received MSI testing (HR = 0.93; 95% CI, 0.91-0.96) or KRAS testing (HR = 0.97; 95% CI, 0.95-1).
Researchers acknowledged study limitations, including its retrospective design and the fact the National Cancer Database does not report patients who did not undergo testing after 2017, limiting inclusion of patients with more recent diagnoses.
“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,” Sabbagh and colleagues wrote. “Further research is encouraged to assess biomarker testing at the state level rather than the regional level, with particular emphasis on sociodemographically vulnerable populations.”
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Sabbagh S, et al. JAMA Netw Open. 2024;doi:10.1001/jamanetworkopen.2024.19142.
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