Aspirin and nonsteroidal anti-inflammatory drugs after but not before diagnosis are associated with improved breast cancer survival: a meta-analysis.

PURPOSE: The association between nonsteroidal anti-inflammatory drugs (NSAIDs) and breast cancer survival is still controversial. The aim of our meta-analysis was to assess the survival benefit of NSAIDs.

METHODS: A literature search was conducted in PubMed and EMBASE (to September 2014). A meta-analysis was performed with hazard ratios (HRs) and 95% confidence intervals (CIs) as the effect measures. Subgroup analyses were based on time of NSAID use (before and after diagnosis), medication type (aspirin and other nonaspirin NSAIDs), and study design (cohort and case-control studies).

RESULTS: There were 16 eligible studies. Use of NSAIDs after diagnosis was significantly inversely associated with relapse/metastasis (HR 0.69, 95% CI 0.59-0.80) and tended toward potentially protective effects on all-cause mortality, although significance was not reached (HR 0.79, 95% CI 0.61-1.02). In cohort studies, the association between post-diagnostic use of NSAIDs and breast cancer survival was stronger with reduced heterogeneity (breast-cancer-specific mortality: HR 0.65, 95% CI 0.48-0.89, I(2) = 65.3%; all-cause mortality: HR 0.73, 95% CI 0.57-0.92, I(2) = 83.2%; relapse/metastasis: HR 0.73, 95% CI 0.61-0.86, I(2) = 48.3%). Aspirin use after diagnosis was significantly associated with breast-cancer-specific mortality (HR 0.69, 95% CI 0.50-0.96) and relapse/metastasis (HR 0.75, 95% CI 0.56-1.00), and tended toward a protective effect on all-cause mortality, although significance was not reached (HR 0.79, 95% CI 0.60-1.03). Including cohort studies only, we obtained similar results and post-diagnostic use of aspirin was significantly associated with all-cause mortality (HR 0.72, 95% CI 0.56-0.93).

CONCLUSIONS: NSAIDs and aspirin after but not before diagnosis were associated with improved breast cancer survival, including breast-cancer-specific mortality, all-cause mortality, and relapse/metastasis.