Mutation Prevalence in mCRC May Differ Based on Certain Patient Characteristics

In metastatic colorectal cancer (mCRC), biomarker positivity rates vary across certain patient characteristics, according to a recent study abstract presented at the annual meeting of the Academy of Managed Care Pharmacy.

The retrospective real-world analysis tested positivity rates of KRAS, NRAS, BRAF, and microsatellite instability (MSI)/mismatch repair (MMR). Across nearly 26,000 patients, at least 4% harbored a mutation in at least 1 biomarker. Their findings, say the abstract authors, support the use of guideline testing recommendations.

Using biomarkers to guide treatment decisions is increasingly being leveraged across various cancers, and CRC is no exception. However, the positivity rates of these biomarkers can differ across different patient characteristics, as was seen in the current study abstract.

“The prevalence of mutations across biomarkers is variable, with KRAS being the most prevalent and NRAS being the least prevalent mutation,” wrote the authors, citing a 44.5% positivity rate for KRAS and 4.1% positivity rate for NRAS. Among the other mutations, 10.7% of patients tested positive for BRAF and 6.3% of patients tested positive for MSI-H/DMMR.

These positivity rates are in line with findings from other research, with physicians citing an approximate 40% positivity rate of KRAS wild-type disease and an approximate 8% positivity rate for a BRAF mutation.

In the current study abstract, the positivity rates for BRAF and MSI-H/dMMR varied based on characteristics like age, sex, race, and Eastern Cooperative Oncology Group (ECOG) performance status at diagnosis. KRAS mutation positivity varied with sex and race, and NRAS mutation positivity varied with race and ECOG performance status.

Patients were included in the study if they were aged at least 18 years, had at least 2 visits in the Flatiron Network, and had at least 2 months of continuous follow-up from the date of their diagnosis. Patients were excluded if they had no interaction with the network within 90 days of receiving their diagnosis or death date prior to their mCRC diagnosis.

Reference

Vieria M, Haniszewski M, Abraham A, Kelton J, Weber C, Edwards M. Real-world biomarker prevalence rates in metastatic colorectal cancer in the United States. Presented at: AMCP 2021; April 12-16, 2021. Abstract C1.