Effectiveness of epidural morphine for the treatment of cancer pain in patients with gastrointestinal neoplasm—a systematic review

One-third of cancer pain patients do not experience adequate pain relief using analgesic ladder by the World Health Organization. Interventional procedures, such as epidural morphine, have been considered. This study aimed to review the literature comparing the effects of epidural administration of morphine with the oral route. This systematic review included randomized controlled trials (RCTs) conducted with patients with gastrointestinal neoplasm. A search was conducted on PubMed, EMBASE, Web of Science, Scopus, Cochrane Library, and CINAHL databases to identify studies published up to May 2023. The retrieved study was evaluated using the Risk of Bias 2 (RoB 2) tool and qualitatively synthesized. The certainty of evidence was assessed using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach (Prospero: CRD42021264728). Only one RCT, a crossover trial, was included in this systematic review. The study was conducted with ten participants (one withdrawal) and reported a statistically significant difference between both subcutaneous and epidural morphine solutions and oral morphine. The adverse events were not described. The included study presents some concerns of bias and low certainty of evidence on the effectiveness and security of epidural morphine administration. The available literature does not suffice to elucidate whether morphine administration via the epidural route is more effective than other routes. Further RCTs are necessary to improve the level of evidence on the effectiveness and risk-benefit of epidural morphine in the management of cancer pain in gastrointestinal neoplasm patients.