EGFR and neoplasm: It is worth noting that all patients with mCRC with RAS PLLM and/or RAS mutation in a limited area of the tumor (i.e., intra- or inter-tumoral heterogeneity) treated with anti-EGFR mAbs had disease progression at 2–3 months (n = 5, cases 2, 7, 9, 11 and 12).