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You’re gonna hear about something called molecular mutations or status on your colorectal cancer in a stage four or metastatic setting. The reason is, is because these give us insight on whether certain drugs will or will not work on you. One of the most important ones we talk about is what’s called KRAS. And you need to know if your’re KRS mutated or KRS wild type, meaning your KRAS is normal. Usually left-sided colorectal cancers are KRAS wild-type, meaning there’s not a mutation there. What this enables is for us to be able to challenge with with what’s called EGFR targeted therapy. Cituximab, panitumumab. These therapies can be used as an adjunct with FOLFOX or FOLFIRI, which are your chemotherapy backbones. If you are KRAS mutated, studies have shown that they do not respond to EGFR targeted therapies, as cituximab and panitumumab. Instead, you’ll probably use something called bevacizumab first-line. This is basically an adjunct that can prevent the recruitment of blood vessels to the tumor. You can also use bevacizumab in KRAS normal or wild type mutations. So bevacizumab can be used in either scenario, but cetuximab, panitumumab and the other EGFR targeted therapies can only be used in KRAS wild-type. As a general rule, when left sided tumors hopefully are more commonly KRAS wild-type, right-sided colon tumors actually are more commonly KRAS mutated than left sided tumors. And for that reason, it’s very important to check because to be normal for KRAS gives you one extra family of agents to use to treat your colorectal cancer.
