Opium use and gastrointestinal cancers: a systematic review and meta-analysis study.

Aim: The current systematic review and meta-analysis aimed to assess the association between Gastrointestinal (GI) cancers and opium use.

Background: GI malignancies are a global public health issue and are associated with many risk factors including genetic and lifestyle factors.

Methods: PubMed, Web of Science, Embase and Scopus and the Google Scholar search engine in addition to Persian databases including Magiran and SID were searched using relevant keywords. The associations of opium use, long duration of opium use, high daily amount opium use and high cumulative opium use and GI cancer and various subtypes of GI cancers were estimated and pooled in format of odds ratios (OR) and their corresponding 95% confidence intervals (CI) with a random effects model.

Results: 22 articles that were published between 1983 and 2022 entered the analyses. There were significant relationships between opium use based on crude effect sizes (OR: 2.53, 1.95-3.29) and adjusted effect sizes (OR: 2.64, 1.99-3.51), high daily opium use (or: 3.41, 1.92-6.06), long duration of opium use (OR: 3.03, 1.90-4.84) and high cumulative opium use (OR: 3.88, 2.35-6.41), all compared to never opium use, and GI cancer. The results were not sensitive to sensitivity analyses and no influential publication biases were found in these analyses.

Conclusion: Our meta-analysis showed that opium use could be associated with increased risk of overall and some particular GI cancers including oropharyngeal, gastric, pancreatic and colorectal cancers. Opium use as a potentially modifiable factor, therefore, should be more emphasized.