According to results recently presented at the 2006 annual European Society for Medical Oncology (ESMO) meeting, results from four years of follow-up continue to indicate that treatment with Femara® (letrozole) significantly reduces the risk of cancer recurrences compared to Nolvadex® (tamoxifen) in postmenopausal women with early, hormone-positive breast cancer. These long-term results also revealed that patients without cancer spread to their lymph nodes benefit from treatment with Femara.
Each year, breast cancer is diagnosed in over 200,000 women in the U.S. alone. Many of these breast cancers will be hormone receptor-positive, meaning that they are stimulated to grow by the circulating female hormones estrogen or progesterone.
Treatment of hormone receptor-positive breast cancer often involves hormonal therapies that suppress or block the action of estrogen. These therapies include tamoxifen as well as agents known as aromatase inhibitors. Tamoxifen acts by blocking estrogen receptors, whereas aromatase inhibitors suppress the production of estrogen.
Among women with metastatic breast cancer, the aromatase inhibitor Femara has been shown to be more effective than tamoxifen. In order to compare Femara to tamoxifen as adjuvant therapy in women with early breast cancer, researchers conducted a phase III clinical trial (the BIG 1-98 trial) among 8,010 postmenopausal women with operable, hormone receptor-positive breast cancer. Women were randomly assigned to one of the following four treatment regimens:
- Five years of tamoxifen
- Five years of Femara
- Two years of tamoxifen followed by three years of Femara
- Two years of Femara followed by three years of tamoxifen
The current analysis includes approximately 5,000 women and compares the two groups who were assigned to receive tamoxifen initially to the two groups assigned to receive Femara initially. Results at a follow-up of two years indicated that Femara significantly reduced the risk of cancer recurrence compared to tamoxifen. Now, researchers have presented results from a four-year follow-up of these patients. Their findings include the following:
- Patients treated with Femara had an 18% reduced risk of a cancer recurrence.
- Patients treated with Femara had a 19% reduced risk of their cancer spreading to other sites in the body.
- Patients whose cancer had not spread to their lymph nodes (node-negative) demonstrated a 12% decreased risk of a cancer recurrence, a risk reduction that was not demonstrated at the two-year follow-up of this trial.
- Women who had received prior chemotherapy had a 26% reduced risk of a cancer recurrence if they were treated with Femara.
- Women whose cancer had spread to the lymph nodes had a 23% reduced risk of a cancer recurrence if they were treated with Femara.
- There was no increase in side effects with longer use of Femara.
The researchers concluded that longer follow-up results indicate that Femara continues to provide a reduction in the risk of cancer recurrences, even to distant sites in the body, at four years among postmenopausal women with early, hormone-positive breast cancer, when compared to tamoxifen. Patients with this disease may wish to speak with their physician regarding their individual risks and benefits of treatment with Femara.
Reference: Coates A, Keshaviah A, Thurlimann B, et al. Five Years of Continuous Letrozole versus Tamoxifen as Adjuvant Therapy for Postmenopausal Women with Endocrine-Responsive Breast Cancer: Further Analyses and Update of BIG 1-98. Proceedings from the 2006 annual meeting of the European Society for Medical Oncology. Istanbul, Turkey. Abstract #2410.