2. Methods
Search strategy
Literature search was carried out in PubMed from the inception to the date up to May 22, 2021 following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines as described elsewhere [41]. Five keywords i.e. “UGT1A1”, “ABCC2” “Polymorphisms”, “Irinotecan” and “Toxicity” was used to search eligible studies in PubMed. Furthermore, relevant refer­ences of retrieved articles were also searched and reviewed for inclusion of eligble studies.