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TOPLINE:

Biomarker testing completion rates in patients with metastatic colorectal cancer (CRC) has increased over time in alignment with guidelines and US Food and Drug Administration (FDA) approvals, but disparities by race, ethnicity, and socioeconomic status persist.

METHODOLOGY:

• Over the past decade, the US FDA has approved several new therapies for metastatic CRC that carry biomarker-based indications. National Comprehensive Cancer Network guidelines now recommend biomarker testing for RAS, NRAS, BRAF, and microsatellite instability (MSI)/mismatch repair protein (MMR) in patients with metastatic CRC.
• In the current study, the researchers wanted to assess biomarker testing trends in this population over the past decade.
• The study included nearly 26,000 adult patients (median age, 64 years), from approximately 280 cancer clinics in the United States, who were diagnosed with metastatic CRC between January 2013 and April 2023 and received at least one line of treatment. Patient data came from Flatiron Health electronic health records.
• The researchers analyzed completion rates for KRAS, NRAS, BRAF, and MSI/MMR biomarker testing as well as how biomarker testing trends changed over time.
• The researchers also assessed factors associated with performing biomarker testing.

TAKEAWAY:

• Among the 25,937 patients included in the analysis, just over half of patients (51.6%) underwent testing for all four biomarkers. Testing rates for each biomarker varied. Overall, 81.6% of patients completed KRAS testing, 73.4% received MSI/MMR testing, 63.7% received BRAF testing, and 60.5% completed NRAS testing.
• Rates of testing for all four biomarkers increased over time, especially for NRAS, BRAF, and MSI/MMR, which is consistent with the timing of guideline recommendations and FDA approvals. Testing for BRAF, for instance, increased from about 31% of patients in 2013 to about 85% of patients in 2023.
• Younger age at diagnosis (≥ 75 years vs < 45 years; odds ratio [OR], 0.40; P < .001), more recent year of diagnosis (2020-2023 vs 2013-2015; OR, 8.56), and lower Eastern Cooperative Oncology Group performance status (4 vs 0; OR, 0.16) were associated with the highest likelihood of completing composite biomarker testing. Higher socioeconomic status index and community (vs academic) practice setting were also associated with higher odds of completing composite biomarker testing.
• Hispanic or Latino vs non-Hispanic or Latino ethnicity (OR, 0.69) and Black vs White race (OR, 0.82) were associated with lower odds of completing composite biomarker testing.

IN PRACTICE:

"Rates of biomarker testing in metastatic CRC have increased substantially overtime as biomarker-driven treatment indications have been approved," the authors said. "However, differences in testing rates are observed based on ethnicity, race, and socioeconomic status, highlighting disparities that require attention."

LIMITATIONS:

The study's retrospective design, incomplete data for all patient variables, and potentially incomplete entry of biomarker testing in database are some limitations of this study.

SOURCE:

This work, led by Hannah R. Robinson from University of Colorado School of Medicine, Aurora, was presented as a poster at the ASCO Gastrointestinal Cancers Symposium 2024 and published online on January 22, 2024 in the Journal of Clinical Oncology.

DISCLOSURES:

The funding source for this work was not disclosed. The authors did not disclose any financial relationships.