Trigeminal neuralgia and risk of cancer: A population-based cohort study.

Background: Evidence of an association between trigeminal neuralgia (TN) and subsequent cancer risk remains sparse. The present study aimed to examine the association between TN and cancer risk in the Danish population.

Methods: A nationwide population-based cohort study using hospital diagnoses collected routinely and prospectively from Danish population-based registries in 1994-2022.

Results: We identified 7846 individuals with a first-time diagnosis of TN. Within one year of diagnosis, we observed 193 cancer cases (standardized incidence rate (SIR) = 2.45, 95% confidence interval (CI) = 2.11-2.82). Absolute risk (AR) for all cancers within one year of TN diagnosis was 2.5% (95% CI = 2.2-2.9). Cancers of the head, neck and nervous system were most strongly associated with TN (AR 0.9% (95% CI = 0.7-1.1); SIR = 13.5 (95% CI = 10.5-17.0)) and the risk was persistently elevated one year after TN diagnosis. We observed 827 cancer diagnoses beyond one year after TN diagnosis, where smoking related cancers were associated with elevated cancer risk (SIR 1.13 = (95% CI = 0.98-1.29)).

Conclusions: TN was associated with an elevated risk of cancers of the head, neck and nervous system including site-specific cancers in the area. Our results suggest the potential importance of smoking related tumors in TN, either as a symptom, cause or shared risk factor.