Meta-analysis showed that, 1 There was no correlation between UGT1A1*6 or UGT1A1*28 gene polymorphism and IRI efficacy; 2 UGT1A1*6 or UGT1A1*28 gene polymorphisms are associated with grade 3–4 diarrhea, grade 3–4 neutropenia, and grade 3–4 leukopenia, and the above-mentioned toxic reactions are more common in wild types (GG and TA6/6). This evidence concerns the gene UGT1A1 and Decreased total leukocyte count.