Does the Use of Two Major Opioids Have an Impact on Improving Pain Treatment and Quality of Life in Cancer Patients?—A Literature Review

Cancer pain is a highly prevalent problem and one of the most distressing symptoms in cancer patients. The management of cancer pain is one of the most significant challenges in the care of these patients. Cancer pain must be treated quickly and effectively as it affects the quality of life and reduces the patient’s life expectancy. Major opioids are recognized by the World Health Organization (WHO) as first-line treatment for moderate to severe cancer pain, but their use is often hampered by individual variations, comorbidities, and complications associated with cancer. Since the simultaneous use of two major opioids has become frequent, a narrative review was conducted, whose main objectives were to evaluate whether the combination of two major opioids improves pain and quality of life in cancer patients, considering their pharmacodynamic and pharmacokinetic properties and evaluate the impact of this combination on the frequency and intensity of side effects. The search for information was carried out in evidence-based medicine databases, namely PubMed/MEDLINE, Cochrane Library, Database of Abstracts of Reviews of Effects, National Guideline Clearinghouse, NHS Evidence and Index das Revistas Médicas Portuguesas using the MeSH terms “opioids” and “quality of life”. Articles and documents published between 1 January 2010 and 1 June 2023, in English, Portuguese and Spanish, were considered, including original articles, meta-analyses, systematic reviews and clinical guidelines. A total of 342 articles were retrieved and of these, only 13 were selected for full reading. The combination of opioids is based on the principle that different opioids act through different mechanisms, which can reduce dose-related adverse effects. Simultaneous use of two major opioids may allow for more modest increases in the equivalent dose of the second opioid, providing better pain control and reduced side effects such as nausea, vomiting, and constipation. More studies on the combination of opioids are needed to improve cancer pain treatment. The lack of personalized therapies limits the effectiveness of opioids, and variability in treatment responses requires individualized approaches. Personalized medicine, based on pharmacogenomics, is one of the most promising strategies to optimize pain relief and reduce adverse effects.