Opium Use and the Risk of Liver Cancer: A Case-Control Study.

Limited evidence is available to acknowledge the association between opium use and liver cancer. In a case-control study, we recruited 117 cases of primary liver cancer (PLC) and 234 age and sex-matched neighborhood controls from 2016 to 2018. We calculated odds ratios (ORs) for opium use and 95% confidence intervals (95% CIs) using conditional logistic regressions. Compared to non-users the adjusted OR (AOR, 95% CI) for opium use was 6.5 [95% CI: 2.87, 13.44]. Compared to people who had no history of use, a strong dose-response effect of opium use was observed by amount of use (AOR: 10.70 [95% CI: 3.92, 28.70]). Cumulative use of opium also indicated that using over 30 gr-year could increase the PLC risk dramatically (AOR: 11.0 [95% CI: 3.83, 31.58]). Those who used opium for more than 21 years were highly at risk of PLC (AOR: 11.66 [95% CI: 4.43, 30.67]). The observed associations were significant even among never tobacco smokers (including cigarette and water-pipe smoking).