EGFR and Decreased total leukocyte count: Compared with the chemotherapy group, combination of chemotherapy and anti-EGFR mAb showed increase in incidences of severe AEs (> = grade 3) that mainly include, leukopenia (OR = 1.53, 95%CI: 1.28-1.82, P < .00001), febrile neutropenia (OR = 1.35, 95%CI: 1.06-1.71, P = .02), hypomagnesemia (OR = 5.68, 95%CI: 3.54-9.10, P < .00001), acneiform rash (OR = 35.88, 95%CI: 17.37-74.10, P < .00001), fatigue (OR = 1.24, 95%CI: 1.02-1.49, P = .03), diarrhea (OR = 1.69, 95%CI: 1.16-2.47, P = .006), and infusion-related reactions (OR = 3.78, 95%CI: 1.93-7.41, P = .0001).