Daily Aspirin Use for Longer than 4 Years Associated with Reduced Long-Term Risk of Cancer Death
Aspirin has been linked to a reduction in the risk of certain colorectal cancers (N Engl J Med 2007 May 24;356(21):2131), but its effect on other cancers is unknown. A new systematic review assessed the relationship between aspirin use and overall cancer mortality using data from 8 randomized trials originally designed to evaluate aspirin for primary or secondary prevention of cardiovascular disease. A total of 25,570 patients were randomized to receive daily aspirin (≥ 75 mg) vs. placebo for ≥ 4 years. There were 674 total cancer deaths during the trials. Aspirin use was associated with reduced risk of cancer death (odds ratio 0.79, 95% CI 0.68-0.92), with an NNT of 106-429, based on 3% cancer mortality in the control groups (level 2 [mid-level] evidence). In a pooled analysis of individual patient data from 7 trials, there was no significant difference in cancer deaths between aspirin and control groups within the first 5 years of follow-up. However at ≥ 5 years, aspirin use was associated with reduced risk of death from any cancer (hazard ratio [HR] 0.66, 95% CI 0.5-0.87), from any gastrointestinal cancer (HR 0.46, 95% CI 0.27-0.77), and from any solid cancer (HR 0.64, 95% CI 0·49-0·85).
Three trials had 20-year follow-up data. In an analysis of 12,659 patients with 1,378 total cancer deaths, aspirin was associated with reduced 20-year risk of death from any gastrointestinal cancer (HR 0.65, 95% CI 0.54-0.78) and from any solid cancer (HR 0.8, 95% CI 0.72-0.88). Aspirin doses were 75 mg/day in 1 trial and ≥ 300 mg/day in the other 2 trials. The benefits of aspirin were similar for the different dosages. The greatest absolute reduction in risk of cancer death occurred in patients ≥ 65 years old (Lancet 2010 Dec 7 early online).
For more information, see the Aspirin topic in DynaMed.
