In addition, a significant association between UGT1A1*6 and neutropenia was observed in all models (G vs. A: OR = 0.57, 95% CI: 0.46–0.71, P=0.00; GG vs. AA: OR = 0.28, 95% CI: 0.17–0.45, P=0.01; GA vs. AA: OR = 0.42, 95% CI: 0.26–0.70, P=0.00; GG+GA vs. AA: OR = 0.32, 95% CI: 0.20–0.52, P=0.00; GG vs. AA+GA: OR = 0.40, 95% CI: 0.22–0.71, P=0.00), whereas, no relationship was found between UGT1A1*6 and clinical response among the different genotypes. Here, UGT1A1 is linked to Decreased total neutrophil count.