June 18, 2013

Aspirin Slows DNA Mutations In Pre-Cancerous Conditions

Lee Rannals for redOrbit.com — Your Universe Online

A new study has determined a possible explanation as to why aspirin is able to lower the risk of some cancers.

Aspirin has been known to lower the risk of cancers, and researchers wrote in the journal PLOS Genetics that the reason why is because the medicine slows the accumulation of DNA mutations in abnormal cells in at least one pre-cancerous condition.

"Aspirin and other non-steroidal anti-inflammatory drugs, which are commonly available and cost-effective medications, may exert cancer-preventing effects by lowering mutation rates," said Carlo Maley, PhD, a member of the University of California, San Francisco Helen Diller Family Comprehensive Cancer Center, and an expert on how cancers evolve in the body over time.

Researchers analyzed biopsy samples from 13 patients with a pre-cancerous condition known as Barrett's esophagus, who were tracked for six to 19 years. The goal of the analysis was to track the rate of mutations in tissues sampled at different times. They performed a crossover study in which some patients started taking daily aspirin for several years and then stopped, while others started taking aspirin for the first time during observation.

The team found that biopsies taken while patients were on an aspirin had accumulated new mutations about ten times slower than biopsies obtained during years when patients were not taking aspirin.

"This is the first study to measure genome-wide mutation rates of a pre-malignant tissue within patients for more than a decade, and the first to evaluate how aspirin affects those rates," Maley said.

Cancers can accumulate mutations over time and more rapidly than normal tissues, and different mutations arise in different groups of cells within the same tumor. The acquisition of key mutations allows tumor cells to grow out of control, and features within a tumor could cause some drug resistance.

The rate of accumulation of mutations measured in the biopsied tissue between time points was slow, even when patients were not taking aspirin. The researchers said the vast majority of mutations arose before the abnormal tissue was first detected in the clinic.

Maley said the findings are consistent with the fact that although Barrett's esophagus is a significant risk factor for esophageal cancer, the majority of cases do not progress to cancer. He said more studies are needed to help determine the link between non-steroidal anti-inflammatory drugs, mutation rates and the development of invasive cancer. He plans to continue studying Barrett's esophagus and esophageal cancer, and to expand his research to investigate lung cancer.

Another group of researchers wrote in the Journal of the National Cancer Institute back in December that people who took aspirin were 41 percent less likely to develop hepatocellular carcinoma (HCC) and 45 percent were less likely to die from chronic liver disease. They said aspirin showed a consistent protective effect related to both HCC incidence and CLD mortality, regardless of the frequency or exclusivity of use.