Aspirin and COX-2 inhibitors like Celebrex will not keep mesothelioma from developing, but they may slow it down a little. That is the conclusion of a team of Australian scientists studying the effects of these drugs on mice and asbestos-exposed people.
Both COX-2 inhibitors (pain relievers which act on a specific enzyme responsible for inflammation) and NSAIDS (non-steroidal anti-inflammatory drugs) like aspirin have been associated with a lower incidence of cancer. In addition, because mesothelioma is known to be triggered, in part, by chronic inflammation caused by asbestos fibers, researchers at the National Centre for Asbestos Related Diseases and the School of Public Health at the University of Western Australia theorized that these drugs might be used to prevent mesothelioma.
To test the theory, researchers gave either 50 mg/kg or 250mg/kg of aspirin in the daily feed to mice with asbestos-induced mesothelioma. At the same time, the team investigated the effects of both NSAIDS and COX-2 inhibitors in 1,738 asbestos-exposed people living or working in the asbestos mining town of Witenoom, Australia. In both cases, the results were disappointing.
“Aspirin did not alter the rate of disease development or increase the length of time that mice survived,” reported lead author Dr. Cleo Robinson in the international journal Lung Cancer. Among the asbestos-exposed human subjects, being on an NSAID or a COX-2 inhibitor (or both) did not appear to have any impact on the incidence of mesothelioma, which continued to occur at a higher-than-normal rate.
The one bit of good news from the study is that, among the mice that were on aspirin, there was a “small but significant” impact on the time it took for mesothelioma to develop (called latency). In people, mesothelioma can take from 10 to 40 years to develop after asbestos exposure. Once it does develop, it typically progresses quickly. Unfortunately, even though the aspirin appeared to stave off mesothelioma development for a while in mice, once the disease took hold, the continued presence of aspirin made no difference.
Australia currently has the highest rate of mesothelioma in the world, due to its asbestos mining history. The country has joined more than 50 members of the EU in instituting a total ban on asbestos and has launched public education campaigns in an effort to reduce the incidence of mesothelioma . The US has not instituted an asbestos ban. About 2,500 Americans contract mesothelioma each year.
Robinson, C et al, “Effect of NSAIDS and COX-2 Inhibitors on the Incidence and Severity of Asbestos-Induced Malignant Mesothelioma: Evidence from an Animal Model and a Human Cohort”, August 18, 2014, Lung Cancer, Epub ahead of print