Nonopioid drug combinations for cancer pain : Protocol for a systematic review

Introduction: Pain related to cancer, and its treatment, is common, may severely impair quality of life, and imposes a burden on patients, their families and caregivers, and society. Cancer-related pain is often challenging to manage, with limitations of analgesic drugs including incomplete efficacy and dose-related adverse effects. Objectives: Given problems with, and limitations of, opioid use for cancer-related pain, the identification of nonopioid treatment strategies that could improve cancer pain care is an attractive concept. The hypothesis that combinations of mechanistically distinct analgesic drugs could provide superior analgesia and/or fewer adverse effects has been tested in several pain conditions, including in cancer-related pain. Here, we propose to review trials of nonopioid analgesic combinations for cancer-related pain. Methods: Using a predefined literature search strategy, trials-comparing the combination of 2 or more nonopioid analgesics with at least one of the combination's individual components-will be searched on the PubMed and EMBASE databases from their inception until the date the searches are run. Outcomes will include pain intensity or relief, adverse effects, and concomitant opioid consumption. Results/Conclusions: This review is expected to synthesize available evidence describing the efficacy and safety of nonopioid analgesic combinations for cancer-related pain. Furthermore, a review of this literature will serve to identify future research goals that would advance our knowledge in this area.