Breast Health |
New Drug Shows Promise Against Advanced Breast CancerExemestane Holds Off Recurrence Longer Than TamoxifenWomen with breast cancer may have a powerful new tool in fighting remission of the disease. The first head-to-head comparison of the drugs tamoxifen and exemestane in women with advanced breast cancer shows the latter was not only safe, it also improves disease-free survival. Exemestane, one of a class of drugs called aromatase inhibitors, is currently approved for women whose cancer progressed while they were taking tamoxifen. Two other aromatase inhibitors are also approved in the US - letrozole and anastrazole. Aromatase inhibition is a method of controlling breast cancer cell growth, in cases where the cancer cells have grown resistant to tamoxifen. "This study is very timely," says Dr. Christiana Brenin, Assistant Professor of Clinical Internal Medicine, and a member of the breast cancer team at UVa's National Cancer Institute's Clinical Cancer Center. "This drug provides additional options for therapy that can improve the outcome of breast cancer care." Studies Show Exemestane SuccessThis latest study comes just days after another clinical trial showed the superiority of taking tamoxifen and exemestane sequentially for five years, as opposed to taking tamoxifen alone for the full five years. The results of these and other studies mark a step forward in the evolution of breast cancer treatment, experts say. UVa's Clinical Cancer Center has been actively involved in clinical trials to test the effective use of aromatase inhibitors, including letrozole and exemestane. For postmenopausal women with estrogen-receptor-positive breast cancer, the gold standard has been to take tamoxifen for five years after initial treatment for the tumor. Tamoxifen, which has been available for 20 years, works by interfering with the ability of estrogen to fuel tumor growth. While many women do benefit from tamoxifen, others fail to respond and, in general, the drug seems to lose its effectiveness after about five years, experts say. Tamoxifen and exemestane both block the growth of breast tumors that respond to estrogen, but the two drugs work in different ways. Tamoxifen interferes with the ability of breast cancer cells to use estrogen for growth, while exemestane interferes with the body's ability to make estrogen. Aromatase inhibitors may be poised to take the place of tamoxifen. As their name implies, these compounds inhibit aromatase, an enzyme that helps make estrogen. Exemestane is actually slightly different from the other two medications in that it has a "steroidal structure." The new study, sponsored by drug maker Pfizer, involved 382 patients from 81 medical centers in 25 countries. The women were randomly selected to receive either tamoxifen or exemestane, but the study was an "open label" one, meaning both physicians and patients knew who was taking which drug. The researchers wanted to see if exemestane would increase progression-free survival by three months over tamoxifen. In fact, the results were slightly better than that. Exemestane also led in other categories. Among the women receiving exemestane, 7.4 percent responded completely to the treatment, versus 2.6 percent of the tamoxifen patients. Also, 36.8 percent of the exemestane participants responded partially to treatment, compared to 26.6 percent in the tamoxifen group. Physicians Look at Best Use for PatientsExemestane has proven effective for women with metastatic breast cancer. But physicians at UVa and other centers are also studying its effectiveness in early stage breast cancer. "We are all very excited about this new class of drugs," says UVa's Dr. Brenin, "because they have fewer side effects, while improving the ability to provide better therapy and longer remission of the disease. While we continue to conduct clinical trials to develop the best guidelines and indications for use, exemestane is FDA approved and very available." Although a number of questions still need to be answered, including how long a woman should take exemestane, the drug does seem poised to take its place alongside tamoxifen, even perhaps instead of it, experts say. How quickly this happens will depend, in part, on whether insurers are willing to reimburse patients for the drug. Exemestane is more expensive than tamoxifen, experts say. What women should take away from this study. "Recent studies of aromatase inhibitors are certainly encouraging" says Dr. Brenin. Exemestane holds promise for the effective management of breast cancer, particularly for women who cannot tolerate tamoxifen. The long-term effects are not yet know, and women with osteoporosis will need to carefully consult with their oncologists, since exemestane increases risk of osteoporosis. UVa's Dr. Brenin concludes, "Women at high risk for breast cancer recurrence would be reasonable candidates for the addition of aromatase inhibitors such as exemestane as part of their therapy. This study provides another potential option in the management of a woman's breast cancer care." Always consult your physician for more information. For additional information about breast health and breast cancer, click here or got to www.uvahealth.com. For current clinical trials related to breast cancer at UVa, click here. Online Resources(Our Organization is not responsible for the content of Internet sites.) American Society for Clinical Oncology Centers for Disease Control and Prevention (CDC) National Cancer Institute Exemestane Study National Institutes of Health (NIH) National Women's Health Information Center Susan G. Komen Breast Cancer Foundation |
May 2004New Drug Shows Promise Against Advanced Breast Cancer Studies Show Exemestane Success Physicians Look at Best Use for Patients What women should take away from this study Blocking Hormone EffectsHormone therapy is used to prevent the growth, spread, and recurrence of breast cancer. The female hormone estrogen can increase the growth of breast cancer cells in some women. Hormones are chemicals produced by glands, such as the ovaries and testicles. Hormones help some types of cancer cells to grow, such as breast cancer and prostate cancer. Hormone therapy may be considered for women whose breast cancers test positive for estrogen or progesterone receptors. A hormone receptor test measures the amount of certain proteins (called hormone receptors) in cancer tissue. Hormones (such as estrogen and progesterone that naturally occur in the body) can attach to these proteins. If the test is positive, it indicates that the hormone is probably helping the cancer cells to grow. In this case, hormone therapy may be given to block the way the hormone works and help keep the hormone away from the cancer cells (hormone receptors). If the test is negative, the hormone does not affect the growth of the cancer cells, and other effective cancer treatments may be given. An antiestrogen drug frequently used, called tamoxifen (Nolvadex®), blocks the effects of estrogen on the growth of malignant cells in breast tissue. However, tamoxifen does not stop the production of estrogen. Side effects that may occur when taking tamoxifen include hot flashes, nausea or vomiting, vaginal spotting, fatigue, headaches, and skin rash. Taking tamoxifen also increases the risk of endometrial cancer (involves the lining of the uterus) and uterine sarcoma (involves muscles of the uterus), both cancers of the uterus. There is also a small risk of blood clots and stroke. A second antiestrogen drug under study for breast cancer prevention, called Raloxifene®, is not recommended for women who have already been diagnosed with breast cancer. Preventing Hormone ProductionDrugs recently approved by the US Food and Drug Administration (FDA), called aromatase inhibitors, are used to prevent the recurrence of breast cancer in postmenopausal women. These drugs, such as anastrozole (Arimidex®) and letrozole (Femara®), prevent estrogen production. Anastrozole is effective only in women who have not had previous hormonal treatment for breast cancer. Letrozole is effective in women who have previously been treated with tamoxifen. Possible side effects of these drugs include osteoporosis or bone fractures. Another new drug for recurrent breast cancer is fulvestrant (Faslodex®). Also approved by the FDA, this drug eliminates the estrogen receptor. This drug is used following previous antiestrogen therapy. Side effects for fulvestrant include hot flashes, mild nausea, and fatigue. Another means of stopping the production of estrogen is the use of surgery to remove the ovaries in women who have not gone through menopause, called an oophorectomy. Always consult your physician for more information. |
