Opioid Conversion in Adults With Cancer: MASCC-ASCO-AAHPM-HPNA-NICSO Guideline Clinical Insights.

Opioid conversion, also known as opioid rotation or switching, is a critical strategy in cancer pain management, necessitated in up to 40% of patients undergoing opioid therapy. In 2025, five leading international organizations-MASCC, ASCO, AAHPM, HPNA, and NICSO-collaborated to produce the first global consensus guideline on opioid conversion in adults with cancer. This review provides clinical insights into the guideline's recommendations, emphasizing individualized care, safety, and evidence-informed practice. Key components include comprehensive preconversion assessment, consensus-based conversion ratios, and vigilant postconversion monitoring. The guideline challenges traditional dose-reduction protocols and addresses controversial areas such as methadone use, transdermal fentanyl conversion, and bidirectional asymmetry. Broader considerations include socioeconomic disparities, stigma, pharmacogenetics, and geriatric-specific concerns. While the guideline offers a robust framework for safer opioid transitions, limitations include reliance on heterogeneous data and the need for clinician expertise. Future directions call for expanded access, education, and integration of personalized medicine approaches to optimize cancer pain management.