My first presentation here at ESMO GI in Barcelona is about the value of sidedness and outcome in colorectal cancer. There have been significant discussions about the prognostic and potential predictive role of right versus left sided location of colon cancers with the idea that left sided tumours do better and they’re more likely to respond to EGF receptor antibodies like cetuximab and panitumumab versus right side tumours which do not appear to respond to panitumumab and cetuximab even if we have a RAS and BRAF wildtype tumour. This is interesting because we look at the same data from a US perspective and a European perspective, Japanese perspective. I’m a member of a guidelines committee in the United States, in Europe and Japan and I see the discussions that we have and we do come to different conclusions. So the title of my talk is actually What’s the Truth? If I had to look at it from an unbiased perspective as much as I can, being a German, raised in Germany, trained in Germany but living in the United States, I believe that for the first line treatment, right-sided tumours, even if they are RAS and BRAF wildtype they should not receive EGF receptor antibodies. Whereas in left sided tumours I think the data are strong enough to say that EGF receptor antibodies should be the default biologic to treat patients in first line colorectal cancer.
I do not think at this point in time that in the later line setting right sided tumours should never be treated with EGF receptor antibodies which is something that is being discussed right now in the United States. So I have a divergent, semi-European opinion about this. I believe that we have another tool at hand to select patients for treatment with EGF receptor antibodies, right and left sided tumours go beyond what we know from RAS and BRAF wildtype tumours.
What is the key message here?
The key message is look at guidelines, look at the sidedness data in conjunction with the mutational analysis that we’re doing, BRAF and RAS mutation. Right-sided tumours, even if they are RAS and BRAF wildtype, no first line treatment with EGF receptor antibodies. Left-sided tumours that’s the default but in later lines of therapy it’s a free game and we should reconsider the use of EGF receptor antibodies.
