# OPRM1 gene polymorphism linked to anxiety in cancer-related pain patients: an observational study

## TL;DR

This study found that a specific OPRM1 gene variant is linked to lower anxiety in cancer patients with pain.

## Contribution

Identified a genetic polymorphism (OPRM1 G allele) associated with reduced anxiety in cancer-related pain patients.

## Key findings

- G allele carriers had significantly lower anxiety scores compared to AA genotype individuals.
- Multivariate analysis showed the G allele is protective against anxiety in cancer pain patients.
- Breakthrough pain, higher pretreatment pain scores, and depression were risk factors for anxiety.

## Abstract

Anxiety is common in patients with cancer-related pain, affecting an increasing number of individuals annually and negatively impacting prognosis. Limited methods are available for early identification of anxiety in these patients. This study explores the link between the OPRM1 gene's polymorphism and anxiety in cancer patients.

We prospectively recruited 76 patients experiencing pain from Yunfu People's Hospital and assessed them with questionnaires on anxiety, depression, quality of life, and other metrics before they commenced opioid treatment. Additionally, Numeric Rating Scale (NRS) scores and opioid usage data were recorded. In situ hybridization was used to analyze the OPRM1 polymorphism rs1799971. Based on the available data, appropriate opioid dosage conversion relationships were established.

This study found that 40.8% (31/76) exhibited anxiety symptoms. OPRM1 genotyping revealed 31.6% AA, 48.7% AG, and 19.7% GG genotypes, conforming to Hardy-Weinberg equilibrium. No genotype differences were found in morphine dosage or NRS pain scores. However, G allele carriers exhibited significantly lower anxiety scores (median 27.0 vs. 36.0, p = 0.017). Multivariate analysis identified G allele (OR = 0.15, p = 0.040) and antitumor therapy (OR = 0.10, p = 0.027) as protective against anxiety, while breakthrough pain (OR = 6.65), higher pretreatment NRS scores (OR = 2.80), and depression (OR = 61.03) were risk factors (all p < 0.05).

Our study indicates that G allele carriers exhibit lower anxiety levels, suggesting a certain correlation between the OPRM1 gene polymorphism and anxiety in cancer pain patients. Furthermore, there is a need to pay increased attention to the psychological health of cancer pain patients with the AA genotype.