The Association Between Aspirin/Nonsteroidal Anti-inflammatory Drugs and Pancreatic Cancer Revisited: An Updated Meta-analysis

Abstract

Purpose: The association between aspirin (ASA)/ other nonsteroidal antiinflammatory drugs (NSAIDs) and pancreatic cancer remains controversial. A meta-analysis done in 2007 showed no association, but recent evidence continues to point to a possible protective effect of prolonged aspirin use on the risk of pancreatic cancer. The aim of this study was to incorporate recent evidence in an updated meta-analysis on the strength and direction of the association. Methods: Two reviewers independently conducted a systematic search of the Cochrane Library, MEDLINE and PubMed database from 1960 to April 2011. Search terms included aspirin, NSAIDs, anti-inflammatory drugs combined with pancreatic and/or gastro-intestinal cancers. Identified articles were reviewed for additional references. Only studies reporting an effect measure for the association between ASA and/or other NSAIDs and pancreatic cancer were eligible for inclusion. In addition to overall effect of ASA/NSAIDs, subgroup analysis by study design(prospective vs retrospective), study setting(USA vs Other countries), duration of exposure (less than or greater than 5 years) and by exposure type (ASA vs. other NSAIDs) were also performed. Analysis was done using the fixed effect model after a preliminary analysis showed no evidence of heterogeneity among all studies and subgroups. Publication bias was assessed using the Begg and Egger tests and visual inspection of funnel plot. All analyses were done using STATA 11. Results: Fourteen (nine prospective and five retrospective) studies were included in the analysis. The overall pooled effect estimate for both ASA and/or NSAID use was 0.99 (95% CI 0.95-1.04). There was no significant association seen in the subgroup analysis by 1) study design: prospective (RR 0.99, 95% CI 0.94, 1.04), retrospective (RR 1.01, 95% CI 0.85, 1.20); 2) setting: USA(RR 0.98, 95% CI 0.92, 1.04), Other Countries (RR 1.01, 95% CI 0.93, 1.09); 3) duration of exposure: less than or 5 years (RR 0.97, 95% CI 0.87, 1.07), More than 5 years (RR 1.12, 95CI 0.91, 1.39); and 4) type of exposure: ASA (0.98, 95% CI 0.92, 1.03), NSAIDs (RR 1.03, 95% CI 0.94, 1.12). Table 1 summarizes the overall and subgroup analysis results.Table 1: . No Caption available.Conclusion: Currently available evidence suggests that there is no association between ASA/other NSAIDs use and risk of pancreatic cancer. This result is not influenced by duration or type of exposure, and study design or country of study.