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* = Presenting author

P342 Meta-analysis: Does aspirin or non-aspirin non-steroidal anti-inflammatory drug use reduce colorectal cancer risk in patients with inflammatory bowel disease?

N. Burr*, M. Hull, V. Subramanian

St. James' University Hospital, Gastroenterology, Leeds, United Kingdom

Background

Inflammatory bowel disease (IBD) patients are at increased risk of developing colorectal cancer (CRC). Aspirin and non-aspirin non-steroidal anti-inflammatory drugs (NA-NSAIDs) have chemopreventive activity against 'sporadic' CRC.

Aim: To investigate whether aspirin and NA-NSAIDs have chemopreventative activity against CRC in patients with IBD.

Methods

We followed a pre-specified and peer-reviewed protocol; the PRISMA statement, a 27 item checklist deemed essential for reporting systematic reviews and meta-analyses of randomized controlled trials and observational studies. We searched for articles reporting the risk of CRC in patients with IBD related to aspirin or NA-NSAID use. No limits or language restrictions were applied. Pooled odds ratios (OR) and 95% confidence intervals were determined using a random-effects model. Publication bias was assessed using Funnel plots and Egger's test. Heterogeneity was assessed using Cochran's Q and the I2 statistic.

Results

Eight studies involving 14917 patients and 3 studies involving 1282 patients provided data on the risk of CRC in patients with IBD taking NA-NSAIDs and aspirin, respectively. The pooled OR of developing CRC after exposure to NA-NSAIDs in patients with IBD was 0.88 (95% CI 0.62 to 1.25) and after exposure to aspirin it was 0.75 (95% CI 0.27-2.08). There was significant heterogeneity (I2> 50%) between the studies. On meta-regression analysis, the population studied (hospital or population-based) was the only factor that almost reached statistical significance (p=0.06). Grouping studies based on the population studied showed that the OR for developing CRC in NA-NSAID users was lower in hospital-based studies (OR=0.44, 95% CI 0.06-3.07) compared to population-based studies (OR=0.91, 95% CI 0.76-1.08).

Conclusion

There is currently no convincing evidence that NA-NSAID or aspirin use is chemopreventive for CRC in patients with IBD. Whilst not reaching statistical significance, the OR for hospital-based studies was lower than population based studies. Hospital-based patients are likely to have more severe disease and so it is possible that NA-NSAIDs and aspirin only exert a significant chemopreventive effect in patients at higher risk of developing CRC. Further large epidemiological studies using prospective databases are needed to clarify the true effect of aspirin and/or NA-NSAIDs on the risk of CRC in patients with IBD. Chemoprevention remains an attractive option due to the poor uptake of surveillance colonoscopy in this group of patients.