Is it time for universal genetic testing in colorectal cancer?

Findings from a recent study show that multigene panel testing of patients with colorectal cancer (CRC) can detect inherited mutations that would not have been identified with guideline-based genetic testing.

The prospective study evaluated universal genetic testing, noting that 1 in 6 patients (16%) with CRC have an inherited genetic predisposition to the cancer. The study showed that more than half of patients with genetic mutations identified in the study would have been missed if they had undergone genetic testing based on current practice. 11% of the patients underwent a change in their treatment, such as the type of surgery or targeted therapy, based on their genetic findings.

The study findings underline the limitations of exclusively relying on current clinical practice guidelines for genetic evaluation, which prioritize testing based on age at cancer diagnosis and family history of the disease.

The study

Researchers used a next-generation sequencing platform that included more than 80 genes in CRC patients. 361 patients with a median age of 57 years participated in the study. 15.5% of patients were identified to have germline mutations. The researchers found that younger age (under 50 years old) was associated with having a germline (inherited) mutation whereas gender, family cancer history, and stage of cancer were not. While current clinical guidelines rely on these characteristics to decide who should be referred for genetic testing, the study findings show that even older patients with CRC have a high rate of pathogenic germline mutations (12%) so by restricting genetic testing to only those under the age of 50 it is likely that clinicians “miss a substantial portion of patients who might benefit from this test.”

The study findings support wide use of genetic testing among all CRC patients, no matter what their age, gender, ethnicity, family cancer history or stage of cancer may be. More prospective studies enrolling large numbers of patients from diverse backgrounds will be needed to best inform the development of best practice genetic testing guidelines.

Take-home message:

Current genetic testing guidelines for patients with colorectal cancer prioritize testing based on age at cancer diagnosis and family history of the disease. Findings from a study suggest that making genetic testing accessible to a wider range of CRC patients could help detect more inherited mutations to inform best treatment decisions.