Researchers turn attention to breast cancer prevention
Scientists work to develop less toxic therapies for women at risk of breast cancer
Cheryl Corbin had her breasts removed after testing positive for the inherited gene mutation linked to the disease. She said she would gladly have taken a pill if it would have reduced her odds of developing breast cancer as much as surgery. (Barbara Haddock Taylor, Baltimore Sun / September 16, 2011)
"I was afraid to hear the words," Corbin, 47, said. "There's no turning back from there."
A genetic counselor tracked her down at the University of Maryland Women's Health clinic, where she is an office manager, and told her that she had the mutation that gave her an 85 percent chance of developing breast cancer. Corbin had no doubt about her next move — she had her breasts removed.
Such wrenching decisions are made by many women at high risk for breast cancer because it's the most effective way to prevent the disease that strikes one in eight women.
But now scientists, dissatisfied with the choices, are advancing other possible preventive treatments to reduce the odds of getting breast cancer.
In laboratories across Baltimore and around the nation, the scientists are testing drugs for prevention. They are also exploring chemical compounds found in broccoli, soy and fat, among others, that may also significantly reduce the risk of side effects of those drugs.
"Prevention is obviously the way to go now," said Angela Brodie, a University of Maryland researcher who helped pioneer a now common set of breast cancer treatment drugs called aromatase inhibitors. "And there's been some significant progress. Step-by-step progress."
A decade ago, Corbin and other patients often only had regular checkups and mastectomy as options for prevention.
More recently, doctors have turned to the drug tamoxifen for prevention. It blocks the effect of estrogen that fuels cancer and lowers risk of getting breast cancer by about 50 percent. But also can cause blood clots and endometrial cancer.
Raloxifene, an osteoporosis drug, also has been added to the prevention toolbox because it also has anti-estrogen effects. Studies have shown it may be slightly less effective than tamoxifen but also a bit less toxic.
Getting the most buzz now are newer versions of Brodie's aromatase inhibitors, widely used for treatment since the 1990s but shown in a study published in June to lower the risk of breast cancer in post-menopausal women by 65 percent.
The aromatase inhibitors are not yet approved by the U.S. Food and Drug Administration for prevention, but Brodie is optimistic. She said they treat breast cancer — and could thwart the disease — by blocking the action of the protein aromatase that helps produce estrogen made in the body after a post-menopausal woman's ovaries stop making the hormone.
She said her research began because she wanted to spare women radical surgery. Now the professor of pharmacology and experimental therapeutics at the University of Maryland's School of Medicine, who was not involved in the latest study, said she is hopeful the drug could not only improve survival rates but perhaps even ensure that women don't ever get the disease.
"That hasn't turned out to be such an easy task," she said. "But we're making progress."
State data from 2006 show the number of new cases of breast cancer annually were about 113 per 100,000 women, and mortality rates were about 25 per 100,000 women, just above the national average.
Taking up the mantle of preventing cancer is a new state task force, the Maryland State Council on Cancer Control, led by Dr. Kathy J. Helzlsouer, director of the Prevention and Research Center at Mercy Medical Center.
She said new preventive drugs are needed because those on the market have such serious side effects. The aromatase inhibitors can cause osteoporosis. She noted a study coordinated by the University of California, San Francisco, which found women were more likely to die after a hip fracture than from breast cancer.
Helzlsouer said there is no one good preventive step for breast cancer, like quitting smoking to reduce lung cancer risk. A balanced diet, for example, is necessary for good health, but there appears only to be a link between obesity and breast cancer in post-menopausal women.
She did say a woman's risk is connected to how early she had her first period (later lowers risk) and first child (later raises risk). Alcohol, exposure to radiation from X-rays and a family history also pose levels of risk. They are considered on the Gail model, a risk assessment tool developed at the National Cancer Institute.