Inclusion and exclusion criteria
All eligible Studies were selected with the following inclusion criteria: (1) clinical trials and
observational studies, (2) studies explored the association betweenUGT1A1*6 and/or UGT1A1*28 or ABCC2 and irinotecan-induced toxicities, (3) studies included patients suffering from neutropenia hematological toxicity and diarrhea (grade III–IV), (4) studies comparing both homozygous and heterozygous versus wild type and (5) studies were published in English.
Exclusion criteria were the following: (1) non-English papers, (2) reviews and case-reports, (3) animal experiments, (4) studies without results about the toxic­ity of neutropenia or diarrhea, (5) studies with undefined genotypes and (6) studies simply focusing on the allele frequency of either UGT1A1*6, *28 or ABCC2 without any correlation with toxicity.