WASHINGTON – Even wonder drugs have their limits: Aspirin use was associated with a significant reduction in the incidence of noncardiac gastric adenocarcinoma, but it had no effect on the incidence of esophageal adenocarcinomas, results of a cohort study suggest.
Among participants enrolled in the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial (PLCO), any aspirin use was associated with a nearly 40% reduction in the incidence of noncardiac gastric adenocarcinoma, whereas the incidence of gastroesophageal adenocarcinoma was numerically but not significantly increased, reported Dr. Jigarkumar A. Patel of the Walter Reed National Military Medical Center in Bethesda, Md.
Ibuprofen, another nonsteroidal anti-inflammatory drug (NSAID), showed a trend toward reduction in the incidence of esophageal adenocarcinoma but did not reach statistical significance.
“The role for aspirin or any other NSAID in cancer prevention still offers hope across some of the other upper gastrointestinal tract malignancies,” Dr. Patel said at the annual Digestive Disease Week.
Mortality rates for esophageal and gastric adenocarcinomas are among the highest of common cancers, with 5-year survival of 18% and 28%, respectively. The incidence of esophageal cancer has risen in the past several decades, with adenocarcinoma in the distal esophagus accounting for most cases in the United States, he said.
A 2011 analysis of individual patient data from randomized controlled trials showed that 5 or more years of aspirin use was associated with significantly lower risk for death from gastrointestinal cancer among all adult age groups, Dr. Patel noted.
To see whether chemoprevention with aspirin or ibuprofen could reduce the incidence of esophageal and gastric cancers, Dr. Patel and his colleagues looked at data on the use of each drug, collected from 1993 through 2001, for 149,024 participants in the PLCO trial. The participants ranged from 55 to 74 years in age and were followed for a median of 12.4 years. The investigators collected data on the incidence of esophageal and gastric cancers for the cohort and created multivariate models to arrive at hazard ratios (HR) for each type of cancer.
There were 487 upper gastrointestinal tract malignancies, which the authors divided by diagnostic codes into either esophageal, cardioesophageal, or noncardiac gastric (i.e., in the distal stomach) adenocarcinomas. They did not include squamous cell malignancies in the analysis.
Any aspirin use was associated with a significant reduction in risk for incident noncardiac gastric adenocarcinoma (HR, 0.61; P = .001). Aspirin had no apparent effects, however, on either esophageal or cardioespohageal cancers.
The strongest effect was seen among participants who reported using aspirin less than once a day but more than once a week (HR, 0.47; P = .005).
As noted before, there was a nonsignificant trend toward a benefit for ibuprofen use against noncardiac adenocarcinomas but only for those who reported it using it daily; weekly or monthly ibuprofen use did not appear to be protective.
“The mixed data could be in part due to some limitations of having multiple confounding factors, such as having Barrett’s esophagus, having reflux disease, having H. pylori, or reverse causation, which is a factor when patients consider taking NSAIDS when counseled by their primary care doctors,” he said.
Dr. Patel said that their findings are similar to those seen in other large cohort studies. However, until the results of randomized, prospective trials of aspirin chemoprevention, such as the study of Aspirin and Esomeprazole Chemoprevention in Barrett’s Metaplasia (ASPECT) and the Aspirin in Reducing Events in the Elderly trial, (ASPREE) become available, prospective cohort studies for evidence of aspirin’s protective effects will have to be relied upon.
The study was supported by the National Cancer Institute. Dr. Patel reported no conflicts of interest.