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Optum and Illumina Inc. researchers documented that less than half of patients with newly diagnosed advanced cancers received any biomarker testing before starting treatment, a gap that persisted despite established guidelines recommending such assessments to guide therapy selection.

Clinicians have faced a rapidly expanding landscape of targeted treatments over the past two decades, with the U.S. Food and Drug Administration clearing multiple biomarker-dependent drugs across tumor types. With so many options becoming available, pressure is mounting to relieve the main bottleneck—testing patients for their biomarkers.

In the study, "Biomarker Testing Approaches, Treatment Selection, and Cost of Care Among Adults With Advanced Cancer, " published in JAMA Network Open, researchers conducted a retrospective cohort analysis to examine testing rates, treatment patterns, and cost impacts across six cancer types.

The cohort included 26, 311 adults diagnosed between 2018 and 2022. Data were drawn from the Optum Labs Data Warehouse, capturing both commercial and Medicare Advantage claims across the United States.

Investigators assigned patients to three groups: no evidence of biomarker testing, non-CGP biomarker testing, and CGP testing, based on claims data from the 90 days preceding systemic therapy initiation. Study measures included per-patient, per-month costs, use of targeted therapy during first-line treatment, and frequency of testing over time.

Overall baseline biomarker testing was 35% (all cancers combined) and rose only to 39% by 2021–22.

Among patients with non-small cell lung cancer, 45% underwent any biomarker testing before treatment initiation, including 22% who received CGP. Ovarian cancer patients had the lowest rates, with just 17% tested. Time trends showed modest improvements, with CGP use for lung cancer rising from 12% in 2018 to 33% in 2021–2022.

Patients receiving CGP were significantly more likely to start targeted therapy. For non-small cell lung cancer, odds of receiving targeted treatment were higher among those with CGP (odds ratio [OR], 3.41; 95% CI, 2.87–4.05) and non-CGP testing (OR, 2.16; 95% CI, 1.80–2.60) relative to patients without testing. Comparable patterns appeared in colorectal cancer (CGP OR, 3.46; non-CGP OR, 1.48).

Cost analyses revealed no statistically significant differences in all-cause per-patient, per-month costs between CGP and non-CGP testing across evaluated cancer types. For example, among breast cancer cases, the cost ratio was 1.03 (95% CI, 0.91–1.17; P = .63).

Patients enrolled in Medicare Advantage plans demonstrated lower or comparable biomarker testing rates compared with those covered by commercial health plans.

Across several cancer types, descriptive results indicated this disparity persisted throughout the study period. For example, in non–small cell lung cancer, the percentage of patients undergoing comprehensive genomic profiling increased over time in both insurance groups but remained lower among Medicare Advantage enrollees.

Investigators conclude that although testing rates increased over time, most patients did not undergo guideline-recommended biomarker assessments before starting first-line therapy.

CGP testing was associated with higher targeted therapy use without increases in treatment-related costs. Broader adoption of CGP could improve alignment between recommended and actual care while preserving economic sustainability.

Written for you by our author Justin Jackson, edited by Sadie Harley, and fact-checked and reviewed by Andrew Zinin—this article is the result of careful human work. We rely on readers like you to keep independent science journalism alive. If this reporting matters to you, please consider a donation (especially monthly). You'll get an ad-free account as a thank-you.

More information: Stacey DaCosta Byfield et al, Biomarker Testing Approaches, Treatment Selection, and Cost of Care Among Adults With Advanced Cancer, JAMA Network Open (2025). DOI: 10.1001/jamanetworkopen.2025.19963 Kenneth L. Kehl, Biomarker Testing in Advanced Cancer, JAMA Network Open (2025). DOI: 10.1001/jamanetworkopen.2025.19972  Journal information: JAMA Network Open

Kenneth L. Kehl, Biomarker Testing in Advanced Cancer, JAMA Network Open (2025). DOI: 10.1001/jamanetworkopen.2025.19972

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