Local study testing drug to prevent breast cancer

Researchers are seeking at least two dozen healthy women in the suburbs North of Boston for an unusual breast cancer prevention study that is raising hopes and concerns.

The study is testing whether a potent drug that is normally used to treat breast cancer could also be effective in heading off the disease in otherwise healthy postmenopausal women who have an elevated cancer risk, due to family history, age or other factors. The North Shore Medical Center's Cancer Center in Peabody is one of six sites in Massachusetts that will soon start enrolling postmenopausal women in the international ExCel trial.

Some activists and bioethicists have questioned the wisdom of giving the drug, known as exemestane, to healthy women when the long-term side-effects are still unknown. Exemestane, also known as Aromasin, was approved by federal regulators in 1999 to treat advanced breast cancer in postmenopausal women.

''Women should know this is research, not treatment, and they should also know what the risks are," said George Annas,a bioethicist at the Boston University School of Public Health.

Annas said people who volunteer for clinical trials often don't fully understand the risks, and they are reluctant to drop out of a study if they experience side effects, because they feel obligated to complete the trial.

Exemestane is part of a family of drugs called aromatase inhibitors that lower estrogen levels. Estrogen fuels the growth of many breast cancer tumors. Researchers are hoping exemestane might provide women with an alternative to tamoxifen, the only drug approved in the US to prevent breast cancer in healthy women. Tamoxifen has potentially serious side effects, including an elevated risk of blood clots, stroke, and endometrial cancer. It has been used for more than 20 years to treat women with advanced breast cancer, compared with the six years exemestane has been on the market

''There is no silver bullet for breast cancer," said ExCel study leader Dr. Paul Goss, director of breast cancer research at Massachusetts General Hospital. MGH and North Shore Medical Center, based in Salem, are members of the Partners HealthCare system.

Goss said concerns of serious, long-term side effects from aromatase inhibitors, such as exemestane, are exaggerated.

''Tens of thousands of women have been treated with [aromatase inhibitors] since 1990 in clinical trials or in treatment for up to five years," Goss said. ''There have been no toxicities found that weren't expected."

Exemestane's known side effects include nausea and hot flashes.

Yet Goss said he is confident the drug's preventative powers will outweigh the risks, based on recent results from other studies of breast cancer patients that found aromatase inhibitors reduced the chances of cancer spreading to the other breast by about two-thirds.

An estimated 211,000 women in the United States will develop breast cancer this year and about 40,400 will die from the disease, according to the American Cancer Society.

Salem grandmother Barbara St. Pierre is well-versed in the numbers. The disease claimed the life of her mother and her older sister, who was St. Pierre's age, 61, when she died three years ago. St. Pierre, who is healthy, is participating in a separate, 5-year breast cancer prevention study involving different drugs.

''There's too much breast cancer going on," said St. Pierre, who has a healthy 35-year-old daughter and two granddaughters.

''I want to help my daughter. I want to help my granddaughters. I want to help any one I can," she said. ''If nobody volunteers for different things then nothing happens."

St. Pierre has been taking two pills a day for over a year, not knowing if she is taking a potent cancer-prevention drug or a placebo. She said she has suffered no side effects. And, she said, she applauds the news of another breast cancer prevention study getting underway.

''If I could volunteer again, I would do it again," she said. ''I will be an advocate to the day I die."

Researchers in the exemestane study hope to enroll 4,500 postmenopausal women in the United States, Canada, and Spain over the next five years. So far, they have enlisted 350. None are from Massachusetts. All will be given a pill for five years, with half the group receiving exemestane and the other a placebo. Goss said scientists will take blood samples from participants in hopes of pinpointing which type of patient, based on her genes, might one day benefit from taking aromatase inhibitors to prevent breast cancer.

With aromatase inhibitors quickly becoming the most commonly prescribed drug to treat breast cancer in postmenopausal women, one large San Francisco-based advocacy group that is worried about the drugs' potential side-effects recently launched an online survey to collect information from women who are taking the drugs as treatment or preventatively, as part of a trial. Breast Cancer Action says it will distribute the results in about a year to the US Food and Drug Administration and cancer institutions.

For more information about Breast Cancer Action survey, visit bcaction.org. For more information about the new exemestane ExCel study, contact the North Shore Medical Center Cancer Center at 978-573-5468 or www.excelstudy.com