In addition, the combination of an anti-EGFR agent with chemotherapy significantly increased some grade 3/4 toxicities including diarrhea (risk ratio {RR} = 1.42, [95% CI, 1.03–1.94], P = 0.03), mucositis (RR = 3.30 [95% CI, 1.54–7.07], P = 0.002), and skin rash (RR = 6.82 [95% CI, 3.15–14.78], P < 0.00001). The gene discussed is EGFR; the disease is mucositis.