A systematic review of oral cancer drug therapies after metabolic bariatric surgery: what oncologists need to know about altered pharmacokinetics

INTRODUCTION: Metabolic bariatric surgery (MBS) may substantially alter the pharmacokinetics of orally administered drugs, yet its impact on oral cancer drug therapies remains poorly characterized. We conducted a systematic review to synthesize the available evidence on the pharmacokinetics of oral anticancer drugs after MBS and identify practical implications for clinical management. AREA COVERED: The search was performed in PubMed, Embase and ClinicalTrials.gov. Studies reporting pharmacokinetic outcomes of oral anticancer agents after Roux-en-Y gastric bypass, sleeve gastrectomy, or one-anastomosis gastric bypass were included. Owing to heterogeneity in study design, drugs, and pharmacokinetic outcomes, a qualitative synthesis was performed. Eight studies involving 33 patients/14 oral anticancer agents were included. Exposure was generally preserved for several biopharmaceutics classification system (BCS) class-I drugs, whereas BCS class-II drugs more frequently exhibited reduced exposure, including pazopanib, sorafenib, and tamoxifen. However, substantial interindividual variability was observed across all BCS-classes, and both under- and overexposure were reported. EXPERT OPINION: Current evidence is scarce and of low certainty. BCS classification may assist in risk stratification, but does not reliably predict post-bariatric drug exposure. Therapeutic drug monitoring should be considered whenever available. Prospective longitudinal pharmacokinetic studies are urgently needed to establish evidence-based dosing recommendations in this growing patient population. REGISTRATION: PROSPERO registration number: CRD420261300203.