Abstract
Despite advancements in colorectal cancer screening and treatment, the occurrence, severity, and mortality rates have consistently risen among younger patients. Precision medicine aims to personalize cytotoxic drug dosages, such as irinotecan, by considering the pharmacogenetic specificity of glucuronidation backgrounds. Our search, focused on recent developments (2020-2024) in categorizing Uridine 5'-diphosphate-glucuronosyltransferase (UGT)1A1 variants related to irinotecan's safety, effectiveness, and cost-benefit in metastatic colorectal cancer patients identified 32 relevant clinical studies and recent reviews from 296 abstracts in PubMed and PubMed Central databases. This updated review emphasizes racial disparities in the incidence and essential variants influencing irinotecan's activated metabolite (SN-38). While UGT1A1*28 homozygosity is the primary cause of toxicity in North America, Europe, and a Middle Asian country, UGT1A1*6 is the prominent variant responsible in East Asian countries. Despite various methods employed for dose adjustment based on pharmacogenomic findings, individualization of the dose has been associated with reduced toxicity, improved response, and enhanced patient survival. The recommended irinotecan dose in the FOLFIRI regimen can be variable between 120mg/m2 to 350 mg/m2 based on the UGT1A1 genotype variant. Moreover, this approach appears to be cost-effective, as suggested by European and Chinese studies.