Background: Although animal studies suggest that nonsteroidal anti-inflammatory drugs (NSAIDs), including aspirin, may protect against cutaneous squamous cell carcinoma (SCC) and actinic keratoses (AKs), possible effects on keratinocytic cancers in humans are unknown.
Objective: We sought to examine the relationship between ingestion of NSAIDs and the risk of SCC and AKs in humans.
Methods: We conducted a case-control study nested within a community-based cohort of 1621 people in southern Queensland, Australia. Eighty-six persons with SCC were compared with 187 age- and sex-matched control subjects randomly selected from within the cohort. NSAID use was captured through face-to-face interviews with study participants, supplemented by color photographs of product packaging. We defined regular use of NSAIDs as consumption of at least two tablets per week (low frequency) or at least 8 tablets per week (high frequency) for at least 1 year. AKs were counted on the face, ears, right hand, and right forearm by a single physician.
Results: Patients with SCC were significantly less likely than control subjects to have used any NSAIDs 8 or more times per week for more than 1 year (multivariate odds ratio [OR] 0.07, 95% confidence interval [CI] 0.01-0.71) and to have used full-dose NSAIDs 2 or more times per week for more than 5 years (OR, 0.20; 95% CI, 0.04-0. 96). Among participants without SCC, current regular users of NSAIDs (> or =2 times per week) had significantly lower counts of AKs than nonusers (rate ratio [RR], 0.52; 95% CI, 0.30-0.91).
Limitations: Estimates of NSAID use were based on self-reported data. Statistical power to detect associations was limited by the number of cases with SCC.
Conclusion: Regular users of NSAIDs appear to have lower risks of SCC and lower counts of AKs than nonusers.