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

Abstract

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.

The carcinogenicity of opium consumption: a systematic review and meta-analysis

“…Cumulative exposure information was available for some studies of cancers of the urinary bladder [8,30,31,43], larynx [8,32], lung [8,33,34], pancreas [8,35,36] and stomach [8,37,55] (never versus ≤ median and > median use). Estimates of association between ≤ median and > median of cumulative opium exposure compared to never use for various cancers in the GCS [8], and for bladder cancer in the IROPICAN study [38] were obtained through personal communication with the study authors (November 2021, and April 2022, respectively). The models included adjustment for age, sex, and tobacco smoking.…”

“…There were 2 prospective cohort studies and 33 case-control studies. There were a total of six new case-control studies identified following the Monographs meeting [30,35,38,[42][43][44]. A total of 15 studies examined the association between opium consumption and bladder cancer (1 cohort and 14 case-control), 7 for laryngeal cancer (1 cohort and 6 case-control), 6 for oesophageal cancer (1 cohort and 4 case-control, one publication [41] describes two separate studies, with different sets of cases and controls), 5 for stomach cancer (2 cohort and 3 case-control), 5 for lung cancer (1 cohort and 4 case-control), and 4 for pancreatic cancer (1 cohort and 3 case-control).…”

“…Several case-control (n = at least 9) studies also used the GCS questionnaire (GCSQ) [7,31,32,34,35,37,41,52,55]. A similarly detailed questionnaire was also used in the IROPICAN study [38,42,43,52]. Other case-control studies ascertained exposure information from telephone calls, face-to-face interviews, patient records or public demographic information and usually characterised exposure as ever/never opium use [5, 17, 19, 22-24, 33, 46, 47, 49-51, 53].…”

“…Some bladder cancer case-control studies relied on patient records and did not define a minimum exposure for 'regular' user (hence the estimate could be interpreted as for an 'ever' user). For bladder cancer, three case-control studies [30,31,38] and for stomach cancer, three of the four case-control studies [37,55] had a measure of intensity of exposure. Exposure quality considerations for most of these studies are extensively described in the published monograph [2].…”

Bladder cancer risk in relation to occupations held in a nationwide case‐control study in Iran

“…Adjustment for opium consumption, which has been recently classified as a human carcinogen, (including for urinary bladder cancer) by the IARC monograph programme, 13 is also important because over 40% of the world's opium use takes place in Iran 34 . The latest study, based on data from the IROPICAN study, shows that the adjusted risk of bladder cancer associated with ever opium consumption is 3.5 (CI: 2.8, 4.3) 35 . After adjustment for this risk factor, the risk of bladder cancer may be significantly affected.…”