| A switch after several years of
tamoxifen to exemestane improves survival for postmenopausal women with early-stage
breast cancer versus continued tamoxifen Postmenopausal women with early-stage breast cancer who switch to exemestane after taking tamoxifen for two to three years following initial treatment have better survival than women who continue tamoxifen, according to a presentation at the annual meeting of the American Society of Clinical Oncology. In the current study, women who switched to the aromatase inhibitor exemestane had a 15 percent lower risk of death than women who continued to take tamoxifen. Exemestane also reduced the risk of breast cancer recurrence and metastasis and development of cancer in the opposite breast. The two drugs were associated with different side effects. “These results show that switching to exemestane after two to three years of tamoxifen is safe and can improve the cure rate in postmenopausal women with breast cancer,” said lead author Raoul C. Coombes, MD, PhD, Professor of Medical Oncology and Head of the Department of Oncology at the Imperial College of London. “Both drugs can be an important part of therapy for these patients.” Tamoxifen is generally given for five years to women with breast cancer to reduce the risk of cancer recurrence. The study, which began in 1998, examined overall survival, breast cancer recurrence and metastasis, and incidence of cancer in the opposite breast in 2,352 postmenopausal women with early-stage breast cancer randomized to exemestane after two to three years of tamoxifen and 2,372 women who continued tamoxifen. In both cases, the goal was to take tamoxifen, or tamoxifen followed by exemestane, for five years. After a median follow-up of 4.8 years since randomization, women in the exemestane group had a 15 percent lower risk of death than women who continued tamoxifen. They also had a 24 percent lower risk of experiencing any first event (such as breast cancer recurrence, a new breast cancer, or dying from something other than breast cancer); a 17 percent reduction in the risk of metastasis; and a 44 percent lower incidence of cancer in the opposite breast. Women who took tamoxifen alone were more likely to develop blood clots or gynecological problems (such as uterine cancer or polyps and vaginal bleeding) than the exemestane group, while women in the exemestane group had slightly more fractures. There were no significant differences in the incidence of myocardial infarction, angina, or stroke between the two groups. The authors stress that women who start exemestane should have baseline and
serial bone density tests to minimize fracture risk. |