Mice studies have revealed that naproxen reduced the incidence of bladder cancer by 75 percent in rats, and intermittent dosing with naproxen (three weeks on the drugs, followed by three weeks off) was highly effective and likely to reduce gastric toxicity.
Naproxen is a non-steroidal anti-inflammatory drug (NSAID), and unlike most NSAIDs and aspirin, it has a lower cardiovascular risk and does increase the risk for gastric ulcers or bleeding. Researchers from the University of Michigan, the National Cancer Institute and the University of Alabama looked at naproxen' effects, with or without proton pump inhibitor omeprazole, on cancer prevention in a rat model of bladder cancer.
They found that naproxen reduced the incidence of bladder cancer by almost 75 percent, and omeprazole by itself did not affect the development of cancer but it also did not interfere with the effect of naproxen at preventing tumors. The rats who received naproxen alone or naproxen with omeprazole developed cancer at similarly low rates, while all rats who received omeprazole alone or no treatment developed bladder cancer.
Lead study author Ronald A. Lubet said, "Our study shows that naproxen works just as well with a proton pump inhibitor as without. This provides proof of principle that this could be a valuable cancer prevention strategy and one hopes it can advance quickly to a clinical trial for those at high risk of colon, esophageal, squamous cell skin cancer or potentially other cancers. The ability to reduce the gastric effects of NSAIDs adds another element to ongoing discussions of whether the NSAID aspirin might be applicable to prevention studies in a more general population, since the gastric toxicity of even low-dose aspirin has been considered a hurdle."
Study author James Scheiman said, "Naproxen is a great candidate for chemoprevention. It comes with a risk of gastrointestinal side effects, but if you can mitigate that with a co-prescription, it's possibly an ideal chemoprevention drug." The researchers hope to plan a clinical trial to look at naproxen plus omeprazole in people at high risk of colon or other cancers.
The study has been published in the American Association for Cancer Research journal 'Cancer Prevention Research'.