The results showed that UGT1A1*28 wild-type (TA6/6) had a statistically significant difference in the incidence of grade 3–4 leukopenia during IRI chemotherapy compared with mutant type (TA6/7 + TA7/7) [RR = 0.64, 95%CI (0.47, 0.86), P = 0.004], as shown in Figure 11. This evidence concerns the gene UGT1A1 and Decreased total leukocyte count.