Charles Fuchs, MD: RAS Mutations and the Sequence of Therapies

Once a patient’s RAS status is known, does this inform the sequence of therapies? How can RAS testing be used to inform later lines of treatment?

In the U.S., the majority of patients receive EGFR antibodies after first line. To be clear, it's perfectly reasonable to give either bevacizumab or an EGFR antibody to patients in the frontline setting if they have a RAS wild type tumor. The practice in the U.S. has historically been to defer EGFR antibodies to later lines. Not that there's evidence that you should do it, it's just that it has been the practice. As such, all RAS testing is best done early in treatment so when you arrive at the point where you need to make a decision where there might be progression, you have in your hands to tell you whether a patient can or should receive an EGFR antibody.

Unresectable Colon Cancer: Case 2

52-year-old woman newly diagnosed with metastatic CRC and is genotyped as part of her initial work up.