Intrathecal Morphine for Colorectal Cancer Surgery: Immediate Postoperative and Post-Discharge Outcomes

Background: Colorectal cancer is a major cause of morbidity and mortality in Australia. Following colorectal cancer surgery, although systemic opioids are often first-line analgesia, they may be associated with various adverse effects. Intrathecal morphine (ITM) has been shown to provide good analgesia with a safe side effect profile. This study assessed whether ITM alongside patient-controlled analgesia (PCA) reduces the incidence of immediate postoperative adverse effects and post-discharge outcomes compared to PCA alone following colorectal cancer surgery. Methods: In this retrospective cohort study, data from 260 patients undergoing colorectal cancer surgery during 2014-2018 at Peter MacCallum Cancer Centre was extracted from a clinical database and medical records. Immediate postoperative outcomes included pruritus, postoperative ileus, and time to mobilisation. Post-discharge outcomes encompassed chronic postoperative pain and long-term opioid consumption. Cancer recurrence was an exploratory endpoint. Comparative analysis was undertaken for ITM with PCA (the ITM group) compared to PCA alone (the PCA group), overall and after stratification into laparoscopy versus laparotomy procedures. Results: In total, 260 patients were included in this study (160 in the ITM group and 100 in the PCA group). The ITM group trended toward a lower incidence of postoperative ileus, lower incidence of chronic pain, and opioid use at three and six months but not at twelve months. Conclusion: Based on the findings, the ITM group trended toward reductions in postoperative ileus, chronic pain, and opioid use at three and six months.