Systemic Opioids for Dyspnea in Cancer Patients: A Real-world Observational Study.

Context. Although Systemic opioids are recommended as a pharmacological treatment for cancer-related dyspnea, their effectiveness and safety needs to be investigated in a real-world context Objectives. To evaluate the effectiveness and safety of systemic regular opioids for dyspnea in cancer patients, in the real -world palliative care practice. Methods. This was a multicenter prospective observational study. We consecutively enrolled adult cancer patients starting regular opioids (morphine, oxycodone, hydromorphone, or fentanyl) for dyspnea from 12 palliative care services across Japan. We evaluated dyspnea intensity using the Numerical Rating Scale (NRS) and Integrated Palliative Outcome Scale (IPOS) every 24 hours until 72 hours after starting opioids (T1-T3). We also evaluated common opioid-related adverse events (AEs) and other severe AEs. Results. We enrolled 402 cancer patients. The proportion of responders was 68.8% (95%confidence intervals (CI): 0.63 -0.74) at T1, 75.7% (95%CI: 0.70-0.81) at T2, and 82.1% (95%CI: 0.76-0.87) at T3. The mean differences in dyspnea NRS from baseline were 1.73 (95%CI: 1.46-1.99) at T1, 1.99 (95%CI: 1.71-2.28) at T2, and 2.47 (95%CI:2.13-2.82) at T3. The most common treatment-emergent AE was somnolence with an incidence of the severe form of approximately 10% through-out the study period. In the multivariate analysis, baseline dyspnea NRS >= 6 had a positive correlation with dyspnea relief by systemic regular opioids, while liver metastasis, clinician-predicted survival days, and opioid tolerance had a negative correlation. Conclusion. Regular systemic opioids were effective for dyspnea in real-world cancer patients.