In the present study, the efficacy and safety of oxycodone and morphine in the treatment of cancer pain were compared in a meta-analysis with the goal of providing a reference for drug selection in clinical practice. Electronic literature databases were searched for articles published through February 2015, including PubMed, MEDLINE, the Cochrane library, and Embase; and the China National Knowledge Intemet, VIP Databases and Wanfang Databases for studies published in Chinese. Only randomized controlled trials were selected. The primary outcome measures were efficacy and the incidence of adverse drug reactions （ADRs）. Data were extracted from the studies by two independent reviewers. A total of 15 studies containing 1338 patients were included in the analysis. The studies were divided into two subgroups according to different scoring methods. The pain relief efficacies of oxycodone and morphine were rated by the numerical rating scale （NRS） （risk ratio [RR]： 1.04; 95% confidence interval [CI]： 0.97-1.11）. Others were rated by the visual analog scale （VAS） （RR： 1.03; 95% CI： 0.97-1.10）. Five studies showed that pain intensity scores did not significantly differ between oxycodone and morphine treatments （standard mean difference [SMD] = 0.16, 95% CI： -0.01-0.33, P = 0.06）. Regarding ADRs, the incidence of constipation was lower in the oxycodone group （RR： 0.70; 95% CI： 0.58-0.85）. No statistical difference was observed among other ADRs. The efficacies of oxycodone and morphine were similar in treating cancer pain. However, the incidence of constipation was lower in patients treated with oxycodone.
