A Systematic Review and Meta-Analysis on Opioid Management of Dyspnea in Cancer Patients.

: Dyspnea accompanies end-of-life in many cancer patients, with around 50% experiencing moderate/severe dyspnea, and is an independent factor for poor prognosis and declining quality of life. Managing dyspnea becomes a key component of palliative treatment and end-of-life support for cancer patients. Opioids seem to be the obvious choice in cancer patients as they also address the pain component (often important in such patients). Evidence-based conclusions on the effectiveness/safety of opioids in dyspnea management are scarce, and the results are still controversial. We aim to address this knowledge gap. : In order to achieve the objective of this paper, we conducted a comprehensive search of international databases (PubMed, Medline, Embase, and Cochrane Library) for randomized controlled trials on the use of opioids to treat refractory dyspnea in adult cancer patients, and we performed a pooled meta-analysis of the results. : The effect of opioids on the relief of dyspnea was significant (SMD -0.44, 95% CI [-0.75,-0.12], = 0.007). The significance of the opioid effect is maintained only for morphine administration (SMD -078, 95% CI [-1.45,-0.10], = 0.02) and only for exertional dyspnea (SMD -1.00, 95% CI [-1.98, -0.03], = 0.04). No correlation was noted between fentanyl/hydromorphone and dyspnea relief or opioids administered for dyspnea at rest. The subcutaneous route seems to be significantly correlated with dyspnea relief (SMD -0.73, 95% CI [-1.27, -0.19], = 0.008), while the other administration modalities lack such an effect. No significant correlation was present between the usage of morphine/fentanyl and increased odds of severe adverse effects (OR 1.48, 95% CI [0.57,3.86], = 0.42); however, fentanyl seems to be associated with increased somnolence. Although we aimed to evaluate how opioids impact the quality of life of cancer patients with dyspnea, we were unable to obtain such results due to the absolute lack of the literature available discussing QoL. : Although we managed to provide some insights into the efficiency and safety of opioids usage for dyspnea management in cancer patients, the evidence based on the available literature is low grade. There is a marked need to address this knowledge gap with future high-quality studies with large sample sizes and standardized protocols.