UGT1A1 and Decreased total leukocyte count: In summary, the polymorphisms of UGT1A1*28 gene were associated with the incidence of leukopenia in cancer patients during IRI chemotherapy, and the incidence of wild type (TA6/6) was higher in mild leukopenia, and the incidence of mutant type (TA6/7 + TA7/7) was higher in severe leukopenia.