EGFR and Skin rash: Among 110 patients treated with cetuximab and irinotecan following disease progression with first-line FOLFOX and a second-line irinotecan-based regimen, patients with a short-repeat variant of the highly polymorphic CA dinucleotide repeat in intron-1 of the EGFR gene were more responsive to treatment and had an increased rate of skin rash than patients with a long-repeat variant of CA99.