People who use painkillers such as ibuprofen on a regular basis may be less likely to get bladder cancer, according to a new review.

The researchers found a smaller chance of the cancer in people taking medications called non-steroidal anti-inflammatory drugs, or NSAIDs, more than twice a week. That includes drugs such as naproxen, marketed as Aleve, and ibuprofen, or Advil.

They did not find a reduced risk of bladder cancer in people who regularly took aspirin, also an anti-inflammatory.

“There’s quite a lot of (research) showing that NSAIDs do protect against a variety of cancers,” Dr. Daniel Djakiew, a cancer researcher at Georgetown University Medical Center in Washington, D.C., told Reuters Health.

The review, which was published in the American Journal of Epidemiology, adds support to previous studies that have suggested that people who take NSAIDs may have a smaller risk of bladder cancer as well as colon cancer and prostate cancer.

It’s possible, said Djakiew, who did not participate in the current study, that “people that chronically consume ibuprofen and maybe other NSAIDs may be getting an anti-cancer benefit that they’re not aware of.”

Bladder cancer is the sixth most common cancer in the U.S. According to the National Cancer Institute, there were about 70,000 new cases diagnosed nationwide in 2010, and close to 15,000 deaths from the disease.

Researchers led by Dr. Sarah Daugherty from the National Institutes of Health combined data from three previous studies. The authors of each of those studies had asked participants how frequently they took different kinds of medications, including aspirin and other NSAIDs, and then tracked how many of them were diagnosed with bladder cancer over the following years.

The studies included a total of more than 500,000 people who were an average of 62 years old at the beginning of the study. Researchers followed them for an average of 7 years.

During that time, about 2,500 people were diagnosed with bladder cancer. More than 4 out of 5 of them were men.

Of people who never took NSAIDs other than aspirin, about 0.54 percent - or 1 in 185 people - developed bladder cancer. In comparison, 0.41 percent of people who took non-aspirin NSAIDs more than twice a week got bladder cancer, or 1 in 244 people.

How often people took aspirin was not linked with how likely they were to get bladder cancer.

Djakiew said there are lots of possible reasons why people who take NSAIDs regularly might be less at risk for bladder cancer. One of those possible explanations, he said, is that inflammation caused by bacteria or a virus, for example, makes the DNA mutations that lead to cancer more likely. By definition, NSAIDs cut down on inflammation, and could therefore reduce the chance of a cancer developing and spreading.

In an email to Reuters Health, Daugherty said that NSAIDs may prevent the growth of bladder cancer cells - and that anti-inflammatories other than aspirin might be better at it than aspirin.

But the study cannot prove that NSAIDs are responsible for lowering the risk of bladder cancer, and the findings don’t mean that taking NSAIDs every day is the best choice for everyone. Such drugs have side effects, including ulcers.

“Based on our results, it would be premature to make recommendations to patients” to take NSAIDs, Daugherty said.

SOURCE: American Journal of Epidemiology, online March 2, 2011.