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. 2024 Jul 1;7(7):e2419142.
doi: 10.1001/jamanetworkopen.2024.19142.

Biomarker Testing Disparities in Metastatic Colorectal Cancer

Saad Sabbagh  1 , María Herrán  1 , Ali Hijazi  1 , Iktej Singh Jabbal  2 , Mohamed Mohanna  1 , Barbara Dominguez  1 , Mira Itani  1 , Kaylee Sarna  3 , Hong Liang  3 , Zeina Nahleh  1 , Steven D Wexner  4 , Arun Nagarajan  1
Affiliations

Biomarker Testing Disparities in Metastatic Colorectal Cancer

Saad Sabbagh et al. JAMA Netw Open. .

Abstract

Importance: Among patients with metastatic colorectal cancer (mCRC), data are limited on disparate biomarker testing and its association with clinical outcomes on a national scale.

Objective: To evaluate the socioeconomic and demographic inequities in microsatellite instability (MSI) and KRAS biomarker testing among patients with mCRC and to explore the association of testing with overall survival (OS).

Design, setting, and participants: This cohort study, conducted between November 2022 and March 2024, included patients who were diagnosed with mCRC between January 1, 2010, and December 31, 2017. The study obtained data from the National Cancer Database, a hospital-based cancer registry in the US. Patients with mCRC and available information on biomarker testing were included. Patients were classified based on whether they completed or did not complete MSI or KRAS tests.

Exposure: Demographic and socioeconomic factors, such as age, race, ethnicity, educational level in area of residence, median household income, insurance type, area of residence, facility type, and facility location were evaluated.

Main outcomes and measures: The main outcomes were MSI and KRAS testing between the date of diagnosis and the date of first-course therapy. Univariable and multivariable logistic regressions were used to identify the relevant factors in MSI and KRAS testing. The OS outcomes were also evaluated.

Results: Among the 41 061 patients included (22 362 males [54.5%]; mean [SD] age, 62.3 [10.1] years; 17.3% identified as Black individuals, 78.0% as White individuals, 4.7% as individuals of other race, with 6.5% Hispanic or 93.5% non-Hispanic ethnicity), 28.8% underwent KRAS testing and 43.7% received MSI testing. A significant proportion of patients had Medicare insurance (43.6%), received treatment at a comprehensive community cancer program (40.5%), and lived in an area with lower educational level (51.3%). Factors associated with a lower likelihood of MSI testing included age of 70 to 79 years (relative risk [RR], 0.70; 95% CI, 0.66-0.74; P < .001), treatment at a community cancer program (RR, 0.74; 95% CI, 0.70-0.79; P < .001), rural residency (RR, 0.80; 95% CI, 0.69-0.92; P < .001), lower educational level in area of residence (RR, 0.84; 95% CI, 0.79-0.89; P < .001), and treatment at East South Central facilities (RR, 0.67; 95% CI, 0.61-0.73; P < .001). Similar patterns were observed for KRAS testing. Survival analysis showed modest OS improvement in patients with MSI testing (hazard ratio, 0.93; 95% CI, 0.91-0.96; P < .001). The median (IQR) follow-up time for the survival analysis was 13.96 (3.71-29.34) months.

Conclusions and relevance: This cohort study of patients with mCRC found that older age, community-setting treatment, lower educational level in area of residence, and treatment at East South Central facilities were associated with a reduced likelihood of MSI and KRAS testing. Highlighting the sociodemographic-based disparities in biomarker testing can inform the development of strategies that promote equity in cancer care and improve outcomes for underserved populations.

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Conflict of interest statement

Conflict of Interest Disclosures: Dr Wexner reported receiving personal fees from ARC/Corvus, Baxter, Becton, Dickinson and Company, GI Supply, Glaxo Smith Kline, ICON Clinical Research Ltd, Intuitive Surgical, Leading Biosciences/Palisade Bio, Livsmed, Medtronic, Olympus, OstomyCure, Stryker, Takeda, Virtual Ports, Karl Storz Endoscopy America, and Unique Surgical Innovations LLC and serving as chair of the Data Safety Monitoring Board of JSR/WCG/ACI, Polypoid, and Boomerang outside of the submitted manuscript. No other disclosures were reported.

Figures

Figure.
Figure.. Study Flow Diagram
MSI indicates microsatellite instability; NCDB, National Cancer Database.
See this image and copyright information in PMC

Comment in

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