A popular arthritis drug shrinks breast cancers in mice and eventually may become a part of breast cancer treatment in humans.

Researchers say the anti-inflammatory drug Celebrex appears to reduce the size of breast cancers by encouraging cancer cell death and stalling the growth of new cancer cells.

Celebrex is part of a class of drugs known as Cox-2 inhibitors, which work by targeting the Cox-2 enzyme that plays a major role in arthritis and inflammation.

Previous studies in animals have suggested that these drugs appear to reduce tumor size and prevent further growth, although the cancer-fighting effects of Cox-2 inhibitors aren’t clearly understood.

Celebrex is already approved to help treat a rare form of inherited colon cancer, familial adenomatous polyposis. And previous studies have shown that Celebrex may also help fight prostate cancer and breast cancer.

Celebrex May Aid in Breast Cancer Treatment

In this study, published in the November issue of Molecular Cancer Research, researchers examined the effects of Celebrex in the treatment of mice with breast cancer.

The results showed that Celebrex seemed to shrink breast cancer tumors by increasing cancer cell death in the breast tissue of mice.

Researchers say this increase in cell death occurred as the result of two separate processes. First, Celebrex increased levels of a protein that is known to foster cell death, and second, it reduced the activity of a protein that protects against cell death.

"This Cox-2 inhibitor represents a strong option for treatment of breast cancers, and a preventative agent for treatment of individuals with high risk of developing breast cancer or disease relapse," says researcher Pinku Mukherjee, PhD, of the Mayo Clinic College of Medicine in Scottsdale, Ariz., in a news release.

Although the results appear promising, researchers say this study was small and further studies are needed in animals and eventually humans before Celebrex can be added to standard breast cancer treatment strategies.

Other Cox-2 inhibitors include Bextra and Vioxx. Vioxx was removed from the market last month due to an increased risk of heart attacks and strokes. Though current research does not suggest that either Bextra or Vioxx have these same cancer-fighting effects, research is under way.

By Jennifer Warner, reviewed by Michael W. Smith, MD

SOURCES: Basu, G. Molecular Cancer Research, November 2004; vol 2: pp 1-11. News release, American Association for Cancer Research.