ASCO Data Shows Anastrozole Offers Breast Cancer Patients Longer Survival
Contact: Julie Penne, (713) 792-0662; [email protected]
DENVER -- Postmenopausal women with advanced breast cancer treated with a new aromatase inhibitor live longer than patients treated with a commonly-used progestin, according to a report given today at the American Society of Clinical Oncology (ASCO).
Dr. Aman Buzdar, professor of breast medical oncology at The University of Texas M. D. Anderson Cancer Center in Houston, reported today (May 20) that postmenopausal patients who failed tamoxifen before receiving anastrozole survive approximately five months longer than similar patients treated with megestrol acetate. In addition to the survival advantage, Dr. Buzdar said the patients treated with anastrozole encountered fewer side effects, thus enjoying a better quality of life.
The median survival time for the patients treated with 1 mg. of anastrozole daily was 26.7 months, while those treated with 40 mg. megestrol acetate four times daily was 22.5 months.
"This is a significant finding in that now we can offer patients with advanced breast cancer who have failed treatment with tamoxifen, the first line of defense against the disease, an opportunity for longer survival and better quality of life," said Dr. Buzdar. "With just one pill a day, these patients can extend their lives and have a better quality of life."
The data is based on two international combined, randomized studies that included 764 patients at 127 institutions. The North American study, headed by Dr. Buzdar, was conducted in the United States and Canada, and the European study was conducted in the United Kingdom, Australia and South Africa.
Patients in the study were divided into three groups. One-third of patients were given 1 mg. of anastrozole daily, another third 10 mg. of anastrozole daily, and another third 40 mg. of megestrol acetate four times daily. All three groups were comprised of postmenopausal women with advanced breast cancer who had failed initial treatment with tamoxifen.
Of the 764 patients, approximately 40 percent of patients in each of the three groups benefited from treatment.
In addition to their disease slowing, patients in both groups receiving anastrozole experienced fewer side effects. Gastrointestinal disturbance was the more common side effect reported by the two groups receiving the anastrozole. A higher fraction of patients who received megestrol acetate experienced significant weight gain which continued to increase while on therapy.
Dr. Buzdar said the promising data from this study has led to two more studies, which may open doors to new uses for anastrozole. He said that while tamoxifen continues as the first-line treatment of breast cancer for postmenopausal women, anastrozole is under additional study as an adjuvant treatment. Adjuvant treatment for breast cancer, frequently chemotherapy, is advised after surgery or another primary treatment to decrease the risk of cancer recurrence.
Dr. Buzdar said another study is also under way to determine if anastrozole may be effective as an initial treatment for metastatic breast cancer.
The Food and Drug Administration (FDA) approved anastrozole approximately 17 months ago after reviewing the first six months of the study's safety and efficacy data. Anastrozole is marketed by Zeneca Pharmaceuticals under the trade name Arimidex. Megestrol acetate is marketed by Bristol-Myers Squibb under the trade name Megace.
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