Prospective cohort study and Mendelian randomization analysis of use of pharmaceutical opioids and subsequent risk of cancer

Opium consumption is classified as ‘carcinogenic to humans’. A prospective cohort study and genetic analyses using the UK Biobank evaluated the association of use of pharmaceutical opioids with subsequent risk of cancer. Associations were analyzed for six established opium-related cancer (lung, pancreatic, bladder, esophageal, oropharyngeal, and laryngeal) and seven non-opium-related cancer (prostate, breast, colon, endometrial, kidney, ovarian, and brain). In the prospective cohort study, regular opioid use was associated with increased risk of opium-related cancer among ever-smoking (aHR 1.33; 95% CI 1.22-1.43) and among never-smoking (1.32; 1.10-1.59) particpants but non non-opium-related cancer (0.96; 0.91-1.02). Both observational and genetic analyses showed increased risk for most opium-related cancers. Except for an inverse association with prostate cancer (aHR 0.83; 95% CI 0.76-0.91), associations were null for non-opium-related cancers. The authors conclude that regular use of pharmaceutical opioids was associated with elevated risk for cancers caused by opium, but not other cancers.