Opioid-sparing effects of ketorolac in palliative care patients receiving opioids for chronic cancer-related pain: A systematic literature review

Standard of care in treatment of cancer-related pain involves opioids in combination with non-steroidal anti-inflammatory drugs (NSAID). Ketorolac, a NSAID, has demonstrated opioid-sparing effects in other clinical settings.This systematic literature review investigated ketorolac's opioid-sparing effects in patients receiving opioids for chronic, cancer-related pain.The primary outcome was total daily dose of opioids. Secondary outcomes included frequency of opioid use, use and frequency of 'rescue' medication and adverse events. Outcomes were described, and meta-analysed where possible. PROSPERO registration CRD42019130894.Articles included original research, from any study phase or methodology, published in English in a peer-reviewed journal or conference between 1990 and 2020; included subjects >18 years; had chronic cancer-related pain and described the use of opioid-sparing effect of ketorolac.Nine articles were included. While there was significant heterogeneity, ketorolac may have an opioid-sparing effect, with significant reductions in total daily dose of morphine observed in a single randomised controlled trial (SMD -4.30 mg, 95% CI -5.36 to -3.25), but the changes in the before and after studies were not statistically significant -0.46 mg (95% CI -1.14 to 0.22). Ketorolac was associated with greater likelihood of complete pain relief, but the data were heterogeneous. Insufficient data were available to analyse frequency of opioid use, or rescue medication requirements.Given the heterogeneity of the data, adequately powered, randomised controlled trials are required to establish any opioid-sparing effect of ketorolac. For patients not responding to conventional pain management, ketorolac may have a role in treatment augmentation.