Practical Application of Molecular Testing in CRC

Transcript:Alan P. Venook, MD: Obviously a patient with stage 2 or stage 3 cancer—stage 2, certainly—should get an MSI status test up front. Now, these days probably 50% to 60% of patients present with stage 4 disease. They already have metastatic disease. What do you do in those patients? I think most of us would get an all-RAS analysis. I do not use much cetuximab or panitumumab in first-line, but it’s not wrong to so. So, I would do an all-RAS analysis. If the patient is all-RAS wild-type, we do test for BRAF because that’s important prognostically.

If the patient has a BRAF mutation, we will almost immediately start thinking about a clinical trial, because the patients don’t do very well with standard of care. The other assays, the MSI, we are doing more and more but it may have very little role in the advanced disease setting, unless the patient’s a candidate later on for something like a checkpoint inhibitor. And, again, HER2 we do not do it in the immediate time frame. Now, at my institution, we have a very robust mentality about the gene testing. We have a 500-gene platform called the UC500. That’s really a research tool. I believe in the community people should do at least those tests that I just commented on.

I think reimbursement is probably the biggest problem, and I do think that there’s a sense in the community that it’s a lot of laying out a lot of money. In fact, most of these assay companies don’t charge. They will someday, but they don’t now. The turnaround time may be 2 to 3 weeks for a multigene assay. That’s a lot. But most cancer patients don’t need to be treated within 1 or 2 weeks. So, what do we have to do immediately? We do, again, RAS, all-RAS, and the BRAF. And that’s to figure out what direction we’re going in. RAS is also a prognostic marker. I think in certain circumstances you might do other tests, such as if the patient is potentially resectable you might want to make sure they’re not BRAF-mutant before you do anything. There are lots of plays you can make. By the way, we haven’t instructed ourselves about what chemotherapy to use, what sequence to use, and so that remains very much up to the practitioner.

Transcript Edited for Clarity