Daily aspirin associated with reduced cancer deaths

Daily aspirin therapy may reduce death from several types of cancer, a new study has shown.

Researchers performed a meta-analysis of randomized trials that compared daily aspirin use with no aspirin use and had a mean duration of scheduled trial treatment of at least four years. The goal of the meta-analysis was to determine the effect of aspirin on risk for death from gastrointestinal and nongastrointestinal cancer. The study results were published online Dec. 7 by Lancet.

Eight trials involving 25,670 patients and 674 deaths from cancer were eligible for inclusion in the study. The authors found that overall, assignment to aspirin therapy reduced cancer death (pooled odds ratio [OR], 0.79; 95% CI, 0.68 to 0.92; P=0.003). Analysis of individual patient data from seven of the trials (23,535 patients, 657 deaths from cancer) found that aspirin's benefit was not apparent until after five years of follow-up (hazard ratios [HR], 0.66; 95% CI, 0.50 to 0.87 and 0.46; 95% CI, 0.27 to 0.77 for all cancer and for gastrointestinal cancer, respectively; P=0.003 for both comparisons). The 20-year risk for death, which was assessed using data on 1,634 deaths from cancer in 12,659 patients in three trials, was also lower in the aspirin groups than in the control groups (HR for all solid cancer, 0.80; 95% CI, 0.72 to 0.88, P<0.0001; HR for gastrointestinal cancer, 0.65; 95% CI, 0.54 to 0.78; P<0.0001). Greater benefit was seen with longer duration of aspirin therapy. Aspirin taken for five years individually benefited esophageal, pancreatic, brain and lung cancer, but more years of therapy were required before an individual effect was seen for stomach, colorectal and prostate cancer. In lung and esophageal cancer, a benefit was seen only for adenocarcinomas. Aspirin's benefit did not seem to be related to dose (75 mg/d and up), sex, or smoking status but did increase as patients grew older, with an absolute reduction in 20-year risk for death from cancer of 7.08% (95% CI, 2.42% to 11.74%) in those at least 65 years of age.

The authors pointed out that they only included trials that assessed daily aspirin use and that the trials did not include enough women to allow assessment of breast cancer or other gynecologic cancer, among other potential limitations. However, they concluded that daily aspirin therapy reduced cancer-related deaths during and after the included trials, with benefit increasing as duration of treatment increased. They called for future studies to examine aspirin's effects on cancer incidence overall and on cancer in women, as well as over longer and shorter periods of follow-up.