Exposure to weak opioids and risk of gastrointestinal tract cancers: A series of nested case-control studies

Martin G. Houston, Úna McMenamin, Brian Johnston, Ronald D. McDowell, Carmel M. Hughes, Peter Murchie, Chris R. Cardwell

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1 Citation (Scopus)


Aims: There is evidence gastrointestinal (GI) motility may play a role in the development of GI cancers. Weak opioids (codeine and dihydrocodeine) decrease GI motility, but their effect on GI cancer risk has not been assessed. We aim to assess the association between weak opioids and cancers of the GI tract. Methods: A series of nested case-control studies was conducted using Scottish general practice records from the Primary Care Clinical Informatics Unit Research database. Oesophageal (n = 2432), gastric (n = 1443) and colorectal cancer (n = 8750) cases, diagnosed between 1999 and 2011, were identified and matched with up to five controls. Weak opioid use was identified from prescribing records. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using conditional logistic regression, adjusting for relevant comorbidities and medication use. Results: There was no association between weak opioids and colorectal cancer (adjusted OR = 0.96, CI 0.90, 1.02, P = 0.15). There was an increased risk of oesophageal (adjusted OR = 1.16, CI 1.04, 1.29, P = 0.01) and gastric cancer (adjusted OR = 1.26, CI 1.10, 1.45, P = 0.001). The associations for oesophageal cancer, but not gastric cancer, were attenuated when weak opioid users were compared with users of another analgesic (adjusted OR = 1.03 CI 0.86, 1.22, P = 0.76 and adjusted OR = 1.29 CI 1.02, 1.64, P = 0.04 respectively). Conclusions: In this large population-based study, there was no consistent evidence of an association between weak opioids and oesophageal or colorectal cancer risk, but a small increased risk of gastric cancer. Further investigation is required to determine whether this association is causal or reflects residual confounding or confounding by indication.

Original languageEnglish
Pages (from-to)2757-2766
Number of pages10
JournalBritish Journal of Clinical Pharmacology
Issue number9
Early online date15 Aug 2023
Publication statusPublished (in print/issue) - 30 Sept 2023

Bibliographical note

Publisher Copyright:
© 2023 The Authors. British Journal of Clinical Pharmacology published by John Wiley & Sons Ltd on behalf of British Pharmacological Society.


  • codeine
  • colorectal cancer
  • gastric cancer
  • gastrointestinal motility
  • gastrointestinal neoplasms
  • oesophageal cancer
  • opioids


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