Opium use and risk of bladder cancer: A multi-centre case-referent study in Iran

Background: Bladder cancer (BC) is the 10th most common type of cancer worldwide and the fourth most common type of cancer in Iran. Opium use is considered as one of the risk factors for BC. We aim to assess the association between various parameters of opium use, which in Iran is mainly ingested or smoked in various forms, and the risk of BC. Method: In this multi-centre case-referent study in Iran, 717 BC cases and 3477 referents were recruited to the study from May 2017 until July 2020. Detailed histories of opium use (duration, amount, frequency) and potential confounders were collected by trained interviewers. Multivariable unconditional logistic regression models were used to measure adjusted odds ratio (OR) and 95 confidence intervals (CI). The ORs were adjusted for age, gender, place of residence and pack-years of cigarette smoking. Results: Regular opium consumption was associated with an increased risk of BC (OR 3.5, 95 CI: 2.8, 4.3) compared with subjects who never used opium. Compared with continuous users, the risk decreased to one-Third for those who stopped opium more than 10 years ago. The adjusted OR for those who used both crude opium (teriak) and opium juice was 7.4 (95 CI: 4.1, 13.3). There was a joint effect of opium and tobacco (OR for users of both opium and tobacco 7.7, 95 CI: 6.0, 9.7). Conclusions: Regular opium use is associated with an approximately 4-fold risk for BC. The OR decreases along with the increasing time since stopping opium use. © 2022 The Author(s) 2022. Published by Oxford University Press on behalf of the International Epidemiological Association

Opium use and the risk of head and neck squamous cell carcinoma

Scant evidence exists to support the association of opium use with head and neck cancer, limited to the larynx and oral cavity. In a multicenter case-control study�Iran Opium and Cancer study, we recruited 633 cases of head and neck squamous cell carcinoma (HNSCC) (254 lip and oral cavity, 54 pharynx, 327 larynx and 28 other subsites within the head and neck) and 3065 frequency-matched controls from April 2016 to April 2019. Odds ratios (ORs) for opium use and 95 confidence intervals (95 CIs) were obtained using mixed-effects logistic regression because of heterogeneity among centers. The adjusted OR (95 CI) for regular opium use was 3.76 (2.96-4.79) for all HNSCC combined. Strong dose-response effects were observed by frequency or amount of use, and duration of use. Regular opium uses significantly increased the risk of HNSCC of the pharynx, larynx and other subsites within the head and neck with OR (95 CI) of 2.90 (1.40-6.02), 6.55 (4.69-9.13) and 5.95 (2.41-14.71), respectively. The observed associations were significant even among never tobacco smokers (including cigarette and water-pipe smoking). Moreover, by the multiplicative interaction scale, the effect of opium use could be varied by cigarette smoking on HNSCC, 8.16 (6.20-10.74). For the first time, the current study showed opium users have an increased risk of several anatomic subsites of HNSCC. © 2020 UIC