Biomarkers and predictors of efficacy of analgesics in the management of cancer pain

Cancer pain continues to be a significant burden to patients and a major therapeutic challenge for physicians. It is well-established that inter-individual differences in responses to both opioids and non-opioids exist. Genetic variations and short nucleotide variants (SNVs) have been attributed to these differences in analgesic efficacy and toxicity, and consequently affect dosing protocols. The purpose of this literature review is to present state- of-the-art evidence regarding biomarkers significantly associated with analgesic efficacy and toxicity related to treatment for cancer pain. A literature search was conducted in Medline and Embase utilizing the keywords “cancer,” “pain,” “pain management,” “inflammation,” and “biomarkers.” Articles that reported on genetic or inflammatory biomarkers associated with cancer pain and/or the clinical efficacy and toxicity of analgesics for the management of pain were considered eligible. A total of 16 articles were included in this systematic review and 52 biochemical and genetic biomarkers were studied. This review demonstrates that limitations in tailored pain therapy, notably in opioid treatment, are manifested in individual differences in analgesic effectiveness and adverse effects. The potential use of biomarkers in the management of cancer pain is an enticing reality; however, there are few instances that a single gene determines the pain phenotype. Future research should focus on large sample populations and genome-wide associated studies to clarify the contradictions in the literature and improve the standard of care.