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 on 6 February 2026, 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 and 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.