Pain polymorphisms and opioids: An evidence based review.

Area of Science:

• Pharmacogenomics
• Oncology
• Pain Management

Background:

• Inter-individual variability in analgesic response is not fully understood.
• Genetic polymorphisms, particularly in cytochrome P450 2D6 (CYP2D6), are implicated but lack clear clinical guidance.
• The need for evidence-based recommendations for genomic profiling in pain management is critical.

Purpose of the Study:

• To review existing evidence and determine if sufficient data supports clinical recommendations for specific genomic profiles in pain management.
• To assess the impact of genetic variations on analgesic administration and efficacy.
• To identify key genetic polymorphisms relevant to cancer pain management.

Main Methods:

• Systematic literature search of PubMed, Evidence Based Medicine Guidelines, and Google up to January 2018.
• Inclusion of systematic reviews, meta-analyses, clinical trials, and guidelines using terms like 'cancer pain', 'polymorphism', 'genetic', and 'gene polymorphism'.
• Application of the Strength of Recommendation Taxonomy (SORT) for evidence assessment.

Main Results:

• Grade A recommendation for OPRM1 A118G (rs1799971) and CYP2D6 polymorphisms influencing morphine response and metabolism.
• Grade B recommendation for COMT rs4680 (Val/Met) affecting opioid efficacy in acute and chronic pain.
• Highlighting of ATP-binding cassette transporter polymorphisms and their role.

Conclusions:

• Consistent data on pain-related genetic polymorphisms is available but has minimal impact on clinical practice.
• Strong evidence supports OPRM1 and CYP2D6 for personalized morphine therapy.
• Polymorphism screening should be considered for patients with persistent, severe, or breakthrough cancer pain.