Abstract
Background Epidemiological studies have reported inconsistent associations between opium use and cancer risk. We therefore conducted a systematic review and meta-analysis to investigate the relationship between opium use and cancer risk. Methods We searched PubMed, Scopus, ISI Web of Knowledge, and Google Scholar until February 2021 and references of retrieved relevant articles for observational studies that reported the risk of cancer in relation to opium use. Random-effects models were used to calculate pooled effect sizes (ESs) as well as 95% confidence intervals (CIs) for the association between opium use and cancer risk by considering opium doses and types, duration of consumption, and routes of opium use. Results In total, 21 observational articles, with a total sample size of 64,412 individuals and 6,658 cases of cancer, were included in this systematic review and meta-analysis. Ever opium users, compared with never opium users, had 3.53 times greater risk of overall cancer (pooled ES: 3.53, 95% CI: 2.60–4.79, P ≤ 0.01). This positive association was also seen for some individual types of cancers except for esophageal and colon cancers. Also, we found that higher opium doses and higher duration of consumption were associated with an increased risk of overall and individual types of cancer. However, the associations between opium doses and the risk of head and neck and larynx cancers were not significant. In terms of the routes of opium use, both opium ingestion and smoking were positively associated with the risk of cancer. Regarding opium types, we found that using teriak, but not shireh, could increase the risk of cancer. Conclusions Our findings showed that opium use, particularly in the form of teriak, is a risk factor for cancer.
Highlights
Opium, the raw extract of opium poppy, is an addictive substance that has been used for recreational or medical purposes [1]
Two articles were published on a case-control dataset [15, 44] and three other articles were published on the dataset of Golestan Cohort Study [27, 45, 46]
The associations between opium doses and the risk of head and neck and larynx cancers were not significant. We found that both opium ingestion and smoking were positively associated with overall cancer risk
Summary
The raw extract of opium poppy, is an addictive substance that has been used for recreational or medical purposes [1]. Is belief might be explained by the analgesic effect of opium Contrary to this belief, recent publications have shown a positive relationship between opium use and some of the mentioned chronic diseases [5, 6]. There are reports on the null association between opium consumption and cancer risk [8, 10] It is not clear whether opium types and doses, as well as the duration and routes of using opium (smoking or ingestion), are involved in the carcinogenic effects of opiates or not. We found that higher opium doses and higher duration of consumption were associated with an increased risk of overall and individual types of cancer. Our findings showed that opium use, in the form of teriak, is a risk factor for cancer
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