Expanding Multigene Panel Testing Criteria for Colorectal Cancer Patients

Multigene panel testing (MGPT) is a tool to identify genetic mutations that can increase an individual’s risk of a disease such as cancer. MGPT can also be used to develop a treatment plan or to help predict whether cancer will spread to other parts of the body. A recent study examined colorectal cancer (CRC) patients and found that 14.2% of patients carried at least one pathogenic germline variant (PGV), with more than one PGV identified in 1.4% of patients. 

Identification of pathogenic or likely PGVs in hereditary cancer predisposition genes can affect a patient’s treatment plan. While there is increased support for universal MGPT for certain forms of cancer, eligibility criteria for CRC are more restrictive: germline genetic testing for CRC is recommended only for a subset of patients with CRC who meet certain “high-risk criteria,” which include:

• Diagnosis before 50 years 
• Lynch syndrome–related cancers 
• Having a family history of certain Lynch syndrome-related cancers 
• Abnormalities in mismatch repair immunohistochemistry

The above mentioned study conducted MGPT across a diverse CRC population to determine whether genetic testing criteria for patients with CRC should be broadened. The results of the study found that of the 34,244 individuals who were tested:

• 14.2% of individuals carried at least one PGV, with more than one PGV identified in 1.4% 
• 11.9% of individuals carried a clinically actionable variant, including 9.1% carrying a PGV in a gene associated with an increased CRC/polyposis risk 
• 5.7% of individuals carried Lynch syndrome–related PGVs 

This research study is the largest to date examining MGPT in CRC, and demonstrated high rates of clinically actionable variants detected, independent of the age at the time of testing, the number of genes on the panel, and race/ethnicity. These findings provide evidence to support the broadening of genetic testing criteria for patients with CRC, which in turn will have a significant impact on disease management, the treatment plan, and ultimately, disease outcome.