Background
We examined the association between opium consumption and pancreatic cancer incidence in a large-scale prospective cohort of the general population in Northeast of Iran.
Methods
A total of 50,045 adults were systematically followed-up (median of 7.4 years) and incident cases of pancreatic cancer were identified. Self-reported data on opium consumption was collected at baseline. Cumulative use (-year) was defined as number of nokhods (a local unit, approximately 0.2 g) of opium consumed per day multiplied by number of years consuming. Adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between opium consumption and pancreatic cancer were calculated using Cox proportional hazards regression models.
Results
Overall, 54 confirmed cases of pancreatic cancer were identified. Opium use of more than 81 nokhod-years (high cumulative use), compared to never use, was strongly associated with pancreatic cancer even after adjustments for multiple potential confounding factors [HR=3.01; 95% CI 1.25-7.26]. High cumulative consumption of opium was significantly associated with risk of pancreatic cancer after adjusting for cumulative dose of cigarette smoking [HR=3.56; 95% CI 1.49-8.50]. In a sensitivity analysis, we excluded participants (including 2 pancreatic cancer cases) who were recruited within the first 5 years of starting opium consumption; high cumulative use of opium was still associated with pancreatic cancer risk [HR=2.75; 95% CI 1.14-6.64].
Conclusion
Our results showed a positive association between opium consumption and pancreatic cancer.
Impact
This is the first prospective large-scale study to show the association of opium consumption with pancreatic cancer as a risk factor.