Negative predictive markers of the anti-EGFR antibody therapies are RAS or BRAF mutations,
while left sidedness can be considered as a positive predictor. Here we analyzed 97
wild type RAS metastatic colorectal cancers looking for the prognostic and predictive
roles of EGFR protein expression. We found that right-sided colorectal cancers are
characterized by significantly higher EGFR protein expression as compared to left-sided
ones, irrespective of the primary or metastatic tissue analysis. Furthermore, tumors
with multiple organ involvement are characterized by significantly higher EGFR protein
expression as compared to single organ ones. In the homogenous cetuximab treated cohort
(n=90) we have found that lower than the applied EGFR protein expression cut-off was
associated with favorable survival. In the multivariate analysis only sidedness proved
to be a strong independent predictor, however sidedness is an EGFR-dependent predictor
of anti-EGFR therapy.
