A recent study in conducted in Canada reveals that breast cancer patients treated with the drug Femara® (letrozole) several years after completing treatment with tamoxifen (Nolvadex®) have a reduced risk of a recurrence. These findings were published in the Journal of Clinical Oncology.
The majority of breast cancers are hormone receptor-positive. These cancers are stimulated to grow by the circulating female hormones estrogen and/or progesterone. Women with hormone receptor-positive breast cancer are often treated with hormonal therapy, such as tamoxifen, for five years following completion of chemotherapy and radiation. Hormonal therapies act by blocking the estrogen from reaching the breast cancer cells, slowing or halting their growth. Femara is also an estrogen-blocking drug that is commonly prescribed to postmenopausal women diagnosed with hormone receptor-positive breast cancer.
Previous research indicates that 50% of breast cancer recurrences and deaths occur five or more years after completing tamoxifen treatment. Additional research has shown that starting treatment with Femara immediately following tamoxifen treatment may help prevent a recurrence. In this study, however, researchers sought to determine if the addition of Femara at any time following tamoxifen treatment could reduce the chance of a recurrence.
Participants in the study were women who had previously been treated with five years of tamoxifen. Each was randomly assigned to receive either a placebo or Femara. Initially, the women were unaware of which group they had been assigned to. But after two years of treatment, participants in the placebo group were given the option of switching to the Femara treatment group. Final analysis was completed on 2,383 women who had been in the placebo group when the option to change to the Femara group was offered. Of these women, 1,579 chose to join the Femara group, while 804 chose not to.
- Women who started Femara at an average of 31 months after completing tamoxifen reduced their risk of breast cancer recurrence by 63% when compared with the women who did not start Femara.
- The risk of cancer spreading to other areas of the body was also reduced by 61% with treatment with Femara.
This study indicates that it may never be too late for breast cancer survivors to protect themselves against future breast cancer recurrences and that Femara may effectively reduce these risks.
Reference: Goss, PE, Ingle, JN, Pater JL, et al. Late extended adjuvant treatment with letrozole improves outcome in women with early stage breast cancer completing 5 years tamoxifen. Journal of Clinical Oncology. 2008