According to results recently presented at the 40th annual meeting of the American Society of Clinical Oncology (ASCO), updated results indicate that Femara® (letrozole) following tamoxifen (Nolvadex®) reduces the risk of death by nearly 40% in postmenopausal women with hormone-positive early breast cancer.1
Early-stage breast cancer refers to cancer that has not spread from its site of origin. Patients with early-stage breast cancer may have cancer that has spread to axillary (under the arm) lymph nodes, but not to distant sites in the body. Standard treatment for early-stage breast cancer depends upon several differing factors, such as the extent of spread of disease (i.e. the size of the cancer and/or number of involved lymph nodes), age of the patient, hormone status of the cancer, overall health of the patient and/or aggressiveness of the cancer. Following the surgical removal of the cancer, some undetectable cells may remain in the body that are responsible for cancer recurrences and ultimately, reduced survival. Therefore, standard therapeutic approaches for early-stage breast cancer often include radiation therapy, hormone therapy and/or chemotherapy in an attempt to kill the remaining cancer cells.
Hormone-positive breast cancer refers to a common type of cancer that is stimulated to grow from the female hormones estrogen (ER) and/or progesterone (PR). Patients with hormone-positive breast cancer are often offered hormonal therapy, a type of therapy that reduces the production or the stimulatory growth effects of estrogen. Tamoxifen has historically been the standard agent used for hormonal therapy in women with hormone-positive breast cancer and is typically used for 5 years. Tamoxifen works by binding to estrogen receptors in a cell so that estrogen is unable to bind, ultimately reducing its growth-stimulatory effects. Recently, however, newer agents referred to as aromatase inhibitors have entered the clinical arena. These agents work by inhibiting the enzyme (protein) aromatase, which is involved in the production of estrogen in the body. Clinical trials are ongoing in an attempt to answer many questions regarding the role of aromatase inhibitors in the treatment of breast cancer, including the timing and sequencing in conjunction with tamoxifen.
The clinical trial, referred to as the MA-17 trial, included over 5,000 postmenopausal women who had completed 5 years of treatment with tamoxifen. Approximately half of these women went on to receive either Femara® or placebo (inactive substitute) and were directly compared. Earlier results from this trial demonstrated a significant reduction in cancer recurrences by 43% in the group of women treated with Femara® compared to placebo.2 More patients treated with Femara® had a reduced quality of life compared to those treated with placebo, including increased bodily pain, hot flashes, pain in the joints and muscles, osteoporosis, and reduced energy and vitality. 3 However, a large proportion of patients considered the side effects to be worth the reduced risk of a recurrence. This trial was stopped prematurely due to the obvious benefits of treatment with Femara® compared to placebo. At the 2004 ASCO meeting, updated survival results were presented from this trial. Overall, the group of women treated with Femara® had an 18% reduced risk of death than those who received placebo. Women with cancer that had spread to the lymph nodes (node-positive) had a 39% reduced risk of death if treated with Femara® compared to placebo. Furthermore, the risk of a recurrence was also reduced by approximately 40% in all women treated with Femara® compared to placebo.
These results indicate that the addition of Femara® following 5 years of tamoxifen significantly reduces the risk of death and cancer recurrence in women with breast cancer, with node-positive patients gaining the greatest survival benefit. Clinical trials are ongoing to determine the optimal timing and sequencing of aromatase inhibitors and tamoxifen in the treatment of hormone-positive breast cancer. Postmenopausal patients with hormone-positive breast cancer may wish to speak with their physician about the risks and benefits of continued Femara® following tamoxifen in their treatment regimen, or the participation in a clinical trial further evaluating the role of aromatase inhibitors. Two sources of information regarding ongoing clinical trials include the National Cancer Institute (cancer.gov) and www.cancerconsultants.com. Personalized clinical trial searches are also performed at cancerconsultants.com.
1.Goss P, Ingle J, Martino S, et al. Updated analysis of the NCIC CTC MA.17 randomized placebo (P) controlled trial of letrozole (L) after five years of tamoxifen in postmenopausal women with early stage breast cancer. Proceedings from the 40th annual meeting of the American Society of Clinical Oncology. New Orleans, LA. 2004. Abstract #847. “Best of oncology symposium” presented June 8, 2004.
2.Goss P, Ingle J, Martino S, et al. A randomized trial of letrozole in postmenopausal women after five years of tamoxifen therapy for early-stage breast cancer. The New England Journal of Medicine. Early publication available at: www.nejm.org. October 9, 2003.
3.Goss, et al. A randomized trial of letrozole in postmenopausal women after five years of tamoxifen therapy for early-stage breast cancer. Proceedings from the 2003 San Antonio Breast Cancer Symposium. December 2003.