Jan. 30, 2006 -- There is more evidence that the same embattled prescription pain relievers suspected of raising the risk of heart attack and stroke may also help prevent certain cancers.
In a newly published study, women who took the drugs Celebrex or Vioxx every day for at least two years were found to have a significant reduction in breast cancer risk, compared with nonusers. Celebrex and Vioxx are part of a class of drugs called Cox-2 inhibitors.
Daily use of other anti-inflammatory pain relievers was also found to be protective, but the Celebrex and Vioxx users had the largest reduction in cancer risk.
Vioxx was taken off the market in the fall of 2004 after research showed that long-term use increased the risk of heart attacks and strokes. Celebrex remains on the market, but questions remain about its cardiovascular safety.
It was reported last month that Celebrex manufacturer Pfizer will finance a $100 million study in hopes of proving that the drug is safe for use by arthritis patients who are also at risk for heart attacks and strokes.
Anti-inflammatory medications work by suppressing inflammation, and inflammation is increasingly believed to play a major role in the development of certain cancers. For this reason, the Cox-2s have been studied as potential anticancer agents.
In addition to raising concerns about its heart risks, the large study that led to the withdrawal of Vioxx also suggested that the drug protects against colorectal cancer by preventing the formation of precancerous colon polyps.
71% Reduced Breast Cancer Risk
The study involved 323 women with breast cancer and compared them with 649 women with no history of cancer matched for age, race, and place of residence. All the participants were questioned to determine their risk factors for breast cancer and their use of Cox-2 inhibitors and other NSAIDs. The women with breast cancer were found to have classic risk factors for breast cancer, including a family history of breast or ovarian cancer, smoking, never being pregnant, and taking or have taken estrogen replacement therapy after menopause.
Researcher Randal Harris, MD, PhD, and colleagues at Ohio State University adjusted for these breast cancer risk factors in their study and concluded that women who used standard doses of either Vioxx or Celebrex every day for two years had a 71% reduction in breast cancer risk.
Taking two or more pills a week of regular aspirin (325 milligrams) had about a 50% reduction in risk, and the risk reduction for users of ibuprofen (such as Motrin or Advil) or naproxen (such Aleve or Naprosyn) was 63%. Baby aspirin (81 milligrams) and Tylenol (a common pain reliever that is not an NSAID) did not show any effect on risk.
The findings are published in the latest issue of the journal BMC Cancer.
More Study Needed
Given the cardiovascular concerns about Cox-2 inhibitors, Harris says much more research is needed before they can be recommended for cancer prevention.
He adds that newer and safer formulations of the current drugs may be on the horizon. Studies could also help determine if lower doses of the drugs than are currently used for pain relief can provide the cancer-prevention benefits without the risks.
"We need to keep looking to tailor the doses and tailor the compounds," he tells WebMD. "We know that they are effective. We just have to balance the side effects and adverse events."
American Cancer Society spokeswoman Debbie Saslow, PhD, tells WebMD that the studies examining the role of Cox-2 inhibitors and other NSAIDs for breast cancer prevention are inconclusive.
Saslow is director of breast and gynecological cancers for the American Cancer Society.
"The data are not yet strong enough to make any recommendations about using these drugs to prevent breast cancer or any cancer," she says. "There are too many unanswered questions about safety."