Dr. McCollum on Molecular Testing in CRC

A. David McCollum, MD, oncologist, Baylor University Medical Center, discusses molecular testing in patients with colorectal cancer (CRC).

Physicians at large tertiary or quaternary referral centers may think that molecular testing is commonly done in patients with CRC, but McCollum states that this is not always the case. Population-based studies reveal that molecular testing is done far less than is commonly believed. McCollum recalls a case he consulted on in which the basic pathology report had no evidence of molecular testing.

Extended RAS profiling is an important test for physicians to consider, as well as KRAS and NRAS tests that look at both the common and less common sites of mutation. While there are the BRAF V600E mutations, there are some non-V600E mutations that, although less common, are probably important to know about, says McCollum. Increasingly in the era of checkpoint inhibitors, physicians want to know about the microsatellite instability status and the mismatch repair gene expression. Those are the foundational molecular features physicians need to know, states McCollum.