Women sought for study of breast cancer drugs

Osteoporosis medication may be safer alternative

May 26, 1999|By Jonathan Bor | Jonathan Bor,SUN STAFF

Hospitals across the nation are recruiting women for a large study to determine whether a drug used to prevent osteoporosis is a safer alternative to tamoxifen in preventing breast cancer.

The study, involving numerous hospitals in metropolitan Baltimore, should answer the question of whether the drug, raloxifene, prevents breast cancer without increasing the risk of uterine cancer and other ills.

About a year ago, doctors concluding a major national trial reported that tamoxifen, long used to treat existing breast cancers, reduced by half the incidence of new cancers in women considered at high risk for the disease.

Although impressive, the drug also doubled a woman's chance of developing endometrial cancer -- cancer of the uterine lining -- leaving patients to decide whether to trade one health risk for another. Recent studies of raloxifene, which measured its effects against the bone-thinning disease osteoporosis, also found a lower rate of breast cancer among women taking the drug.

Results of the studies left doctors wondering if the drug might be as effective as tamoxifen in preventing breast cancer, only safer.

"Women who are at increased risk for breast cancer need options for preventing this disease with a minimum of side effects," said Dr. Leslie Ford, who is overseeing the National Cancer Institute trial.

The trial will last five years and include 22,000 women at 400 centers in the United States, Canada and Puerto Rico. The women will be randomly assigned to take one drug or the other and will have regular mammograms, breast and gynecological examinations and blood tests.

In Baltimore, Franklin Square Hospital Center, University of Maryland Medical Center and Johns Hopkins Hospital will recruit and monitor patients. Franklin Square will also supervise participation at several other facilities: Harbor Hospital Center, Union Memorial Hospital, St. Agnes HealthCare, Mercy Medical Center, St. Joseph Hospital and Greater Baltimore Medical Center.

The Franklin Square consortium also includes medical centers in Frederick, St. Mary's County and Washington.

To participate, a woman must be postmenopausal, at least 35 and healthy but at increased risk for breast cancer. Risk is determined by a formula that takes into account age, family history and past evidence of a precancerous breast lesions.

Dr. George Elias, a cancer surgeon directing the Franklin Square contingent, cautioned against concluding anything about raloxifene's cancer-fighting abilities until the study is completed. The osteoporosis study was encouraging, he said, but far from conclusive.

"We can't make any claims unless it is proven," Elias said.

The two drugs behave similarly in the human body, blocking the female hormone, estrogen, in some tissues while promoting it in others.

Most importantly, the drugs appear to block estrogen in breast tissue, where the hormone can trigger cancer. They appear to have the same beneficial effects as estrogen on bones, preventing them from becoming porous and vulnerable to fracture.

To complicate the issue, tamoxifen also stimulates the uterine lining to grow -- an effect linked to the higher rates of endometrial cancer among women taking the drug. So far, doctors say, raloxifene appears not to have this effect on the uterus.

Dr. Kathy Helzlsouer, director of the Hopkins Breast and Ovarian Surveillance Service, said she expects a high level of participation in the study. Unlike the earlier tamoxifen study, in which half the women were given a placebo, everyone in this study will be offered a drug that carries some benefit.

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