Femara® Improves Cancer-free Survival in Early Breast Cancer

Cancer Connect

According to the results of a Phase III clinical trial published in the Journal of Clinical Oncology, adjuvant (post-surgery) treatment of hormone receptor-positive early breast cancer with the aromatase inhibitor Femara® (letrozole) results in better cancer-free survival than treatment with tamoxifen.

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.

In order to compare the aromatase inhibitor 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 focused on the 4,922 women in the first two study groups (five years of tamoxifen or five years of Femara). A majority of these women have now been followed for more than four years.

  • The estimated probability of surviving for at least five years without a cancer recurrence or a new cancer was 84% among women treated with Femara and 81% among women treated with tamoxifen.
  • There was no difference between study groups in overall survival.
  • Women treated with tamoxifen were more likely than women treated with Femara to experience blood clots, changes to the uterine lining, hot flashes, night sweats, and vaginal bleeding. Women treated with Femara were more likely to experience bone fractures, joint pain, high cholesterol levels, and certain cardiovascular problems.

The researchers conclude, This analysis adds to the body of data supporting a role for the inclusion of an aromatase inhibitor in the adjuvant therapy of postmenopausal women with receptor-positive early breast cancer.

Reference: Coates AS, Keshaviah A, Thürlimann B et al. Five Years of Letrozole Compared with Tamoxifen as Initial Adjuvant Therapy for Postmenopausal Women with Endocrine-responsive Early Breast Cancer: Update of Study BIG 1-98. Journal of Clinical Oncology [early online publication]. January 2, 2007.

Related News:Four-year Results Continue to Show Superior Outcomes with Femara® in Early Breast Cancer (10/16/2006)

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