Breast Cancer Study Focuses on Post-Menopausal Women

As women grow older, their risk for breast cancer increases dramatically. A woman in her thirties has a one in 227 chance of getting breast cancer, while a woman in her sixties has a one in 26 chance, according to the National Cancer Institute. A new study being conducted in part at the Medical College of Wisconsin puts the focus on postmenopausal women and breast cancer. The study, coordinated by the National Cancer Institute of Canada Clinical Trials Group with the support of Pfizer, Inc. and in cooperation with women's health and cancer centers in the United States, Canada and Spain, is designed to determine whether a special type of medication can prevent breast cancer in this specific group of women.

"We are fortunate to be one of the institutions selected to participate in this study, which began about one and one-half years ago. We'll be enrolling women over a period of three years. The goal for our site is to enroll 200 women," says Nordeana Nimphius, MS, Clinical Research Coordinator in the Department of Obstetrics and Gynecology at the Medical College of Wisconsin. "Our hope is that the results of this study will have an impact on the future of breast cancer prevention," she added.

The study, called the ExCel research study, will analyze the potential benefit of a drug called exemestane, a member of a class of drugs called aromatase inhibitors. "Exemestane has been approved by the US Food and Drug Administration and is already being used with good results. A 2004 study showed that for women who had breast cancer in one breast, it was effective in preventing the occurrence of new cancers in the other breast," says Nimphius. "What we would like to find out is will it prevent breast cancer in women who have never had breast cancer?"

Side Effects
Another drug, Tamoxifen, has been in use since 1998 to reduce the incidence of breast cancer in women who are at high risk of developing the disease. However, it has been shown to have some serious negative side effects. "Tamoxifen may cause cancer of the uterus as well as blood clots, especially in older women. As a result, women need to seriously consider whether or not they want to take the drug. Exemestane may prove to be an alternative," Nimphius says.

After menopause, a woman's ovaries cease production of estrogen, but her body continues to make it from skin, muscle and fat. Although it is present at much lower levels, estrogen is still important in the development of most types of breast cancer. "Exemestane works in a different way than Tamoxifen. It targets and binds to an enzyme that is required to produce estrogen. Without estrogen, most breast cancer cells can't survive," Nimphius explained.

Fortunately, exemestane does not appear to have the dangerous side effects present with Tamoxifen. "It is generally well tolerated and the side effects are quite predictable. Most common are low grade nausea, hot flashes, and general muscle aches and pains," Nimphius says.

Who Can Participate
"We are trying to determine the length of a woman's exposure to estrogen," Nimphius explained. "We want to enroll women who are at high risk for breast cancer." You may be able to participate if:

• you are 35 years of age or older
• you are postmenopausal (not having monthly periods)
• you are at increased risk for developing breast cancer

How do you know if you are at increased risk? Both genetic and environmental factors are believed to play a role in a woman's risk of developing breast cancer. For example, if either a woman's mother or sister has breast cancer, the woman's risk increases about two to three times, according to the National Cancer Institute.

Some of the factors that increase your risk for breast cancer are:

• age (anyone over age 60 is eligible to participate in the study)
• family history of breast cancer (especially mother and sisters)
• number of breast biopsies
• atypical mammograms
• early onset of first menstrual period
• age at time of first live birth (especially if it is after age 30)
• no pregnancies

Another risk factor among postmenopausal women appears to be excess weight and high body mass index.

Study Design
The ExCel study is a so-called "double-blind" research study in which women will be randomly assigned to one of two treatment groups. All the women in the study will take one pill a day for five years. One group will get a tablet of exemestane every day, while the other group will get one tablet of a placebo per day (a placebo is an inactive substance that does not contain any of the medicine being studied in the trial). No one participating in the study - physicians, research scientists or subjects - will know who is receiving the real drug and who is receiving the placebo until the end of the study.

"Of course, there are safety checks taking place constantly. A safety monitoring board meets every six months for the duration of the study. Even though exemestane reduces the chance, we do expect to see some breast cancer. If any subject encounters a problem, it will not mean the end of the study, but we would release that person from the study immediately," Nimphius said.

About Participating
If you are interested in participating in the ExCel research study, you are required to have a screening visit with a member of the study's clinical staff to see if you may be eligible. "We will determine your breast cancer risk by asking questions about family history and other health issues," notes Nimphius. "If a woman is eligible, she must have a routine health examination, baseline mammogram and bone density test as well as some routine blood tests."

"I would really encourage women to participate in the study. They have a fifty-fifty chance of getting the drug. If they are at high risk for breast cancer, it is an alternative to taking Tamoxifen," Nimphius says. The study is gaining participants from around the world. "Patients are enrolling from the United States, Canada, Puerto Rico and Spain. Results of the study will be available four to five years from now, unless there is a problem with side effects."

Women who would like more information about the ExCel research study should contact Nordeana Nimphius at (414) 805-4763 or visit www.excelstudy.com.

JoAnn Petaschnick
HealthLink Contributing Writer

MCW Health News presents up-to-date information on patient care and medical research by the physicians of the Medical College of Wisconsin.