While a false negative result (no mutation detected in a patient with a RAS mutant tumor) in either tissue or plasma may lead to the inappropriate assignment of first-line treatment anti-EGFR therapy (with the risk of detrimental outcome with anti-EGFR exposure, the risk of toxicity and/or allergic reaction and the high expenses associated with these agents), this risk is largely mitigated by the high frequency of radiographic surveillance in mCRC patients undergoing therapy. Here, EGFR is linked to allergic disease.