Methadone switching for refractory cancer pain

BACKGROUND: Methadone is commonly considered an alternative opioid treatment for refractory cancer pain. This study aims to investigate the efficacy, safety, and cost of methadone in the treatment of refractory cancer pain. METHODS: A retrospective study was conducted in patients who used methadone for refractory cancer pain from April 2016 to December 2020 at a cancer specialized hospital. Pain control, evaluated via pain score and breakthrough pain frequency, and adverse events of methadone were compared with analgesic regimens prior to methadone administration. The factors potentially affecting the switching outcome were analyzed via multivariate analysis. Moreover, the cost of pain control was estimated. RESULTS: Ninety patients received methadone for poor pain control (74.4%), intolerable adverse events (10.0%), or both (15.6%) after prior opioid treatments. Sixty-four patients (71.1%) were successfully switched to methadone with median pain score significantly decreased from 4.0 to 2.0 (p < 0.001) and median daily frequency of breakthrough pain from 3.0 to 0.0 (p < 0.001) at a maintained median conversion ratio of 6.3 [interquartile range (IQR): 4.0–10.0] to prior opioid treatment. Similar adverse event profiles of constipation, nausea, vomiting, and dizziness were observed between methadone and prior opioid regimens. The median daily cost of analgesic regimens was significantly reduced from $19.5 (IQR: 12.3–46.2) to $10.8 (IQR: 7.1–18.7) (p < 0.01) after switching to methadone. The 3-day switch method significantly improved the rate of successful switching compared with the stop and go method (odds ratio = 3.37, 95% CI: 1.30–8.76, p = 0.013). CONCLUSION: Methadone is an effective, safe, and cost-saving treatment for patients with refractory cancer pain.