High Prevalence of Cannabinoid Receptor 1 Expression in Thai Patients with Cholangiocarcinoma and Its Prognostic Implications.

Ungtrakul T.; Amatawet C.; Sricharunrat T. · Asian Pacific journal of cancer prevention : APJCP · 2026

**Background & Methods** This retrospective cohort study analyzed tumor tissue from 51 Thai patients with histologically confirmed cholangiocarcinoma (CCA) treated at a tertiary cancer center between 2014-2018. Cannabinoid receptor 1 (CB1) expression was assessed via immunohistochemistry with semi-quantitative scoring based on staining intensity and extent, and associations with clinicopathological features and survival outcomes were evaluated. **Key Findings** - High CB1 expression was detected in 46 of 51 cases (90%), demonstrating widespread overexpression of cannabinoid receptors in Thai CCA patients - Patients with high CB1 expression more frequently presented with advanced-stage disease (stages III-IV); however, no statistically significant difference in overall survival was observed between high and low CB1 expression groups (median OS 18.5 vs. 23.0 months; p = 0.68) - The study population was predominantly intrahepatic CCA (80%), with median age of 59 years and 41% female representation; 47% had advanced-stage disease at presentation **Dosage & Administration** Not reported. **Safety & Adverse Effects** Not reported. **Evidence Quality** This study has significant limitations that restrict the strength of conclusions. The small cohort size (n=51) substantially limits statistical power to detect meaningful associations between CB1 expression and clinical outcomes. The retrospective design introduces potential selection and information bias, and the single-center Thai population may limit generalizability to other geographic regions and populations. The lack of statistically significant survival differences may reflect insufficient sample size rather than true absence of effect. Additionally, the study provides descriptive analysis of CB1 prevalence without mechanistic investigation or therapeutic intervention, limiting direct clinical applicability. The authors appropriately acknowledge these limitations and call for larger prospective studies to clarify CB1's biological and therapeutic relevance in CCA. The high prevalence of CB1 expression (90%) is noteworthy and suggests potential therapeutic targeting; however, current evidence is insufficient to support clinical recommendations regarding cannabinoid-based interventions for CCA management.

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