New research backs up earlier reports that the breast cancer drug Femara can reduce the risk of breast cancer recurrence by nearly 50 percent in women previously treated with tamoxifen.
A five-year study of the Femara treatment given after tamoxifen therapy was halted early after the survival benefits of Femara became clear. Now a study in the Journal of the National Cancer Institute provides complete analysis of the data after an average of two-and-a-half years of follow- up.
The results show that 3.6 percent of the postmenopausal women with breast cancer who took Femara after five years of treatment with tamoxifen experienced a recurrence. Six percent of those who received the placebo after tamoxifen treatment experienced a recurrence of breast cancer.
Breast Cancer Drug Fights Recurrence
Women who have survived breast cancer are at high risk for a recurrence of the cancer. Therefore, the standard treatment after surgery or radiation for estrogen-sensitive breast cancer is five years of tamoxifen. It works by blocking the effects of the hormone estrogen, which helps some breast cancers grow.
But after five years of treatment, the survival benefits of the tamoxifen decrease. That’s where a newer group of drugs known as aromatase inhibitors, such as Femara, comes in. Aromatase inhibitors lower the levels of estrogen in the body by acting on the aromatase enzyme involved in making estrogen.
In the study, researchers assigned more than 5,000 postmenopausal women who had previously taken tamoxifen for breast cancer to take either Femara or a placebo for another five years.
The results showed that after two-and-a-half years of follow-up, women taking Femara had a significantly lower risk of breast cancer recurrence.
Survival free of breast cancer was significantly lower in women taking Femara, although overall survival rates among the two groups were similar.
The researchers also show that women taking Femara with lymph-node-positive breast cancer had significantly better survival rates than those on the placebo.
Femara Side Effects
The drug was generally well tolerated, but women taking Femara had side effects related to the drops in estrogen that are consistent with the effects of the drug. Side effects included:
—Osteoporosis: 8.1 percent of women taking Femara were diagnosed with osteoporosis compared with 6.0 percent in the placebo group.
—Hot flashes: 58 percent of women taking Femara reported having hot flashes compared with 54 percent of those on placebo.
—Hair loss: Loss of hair was more common in those taking Femara, but it was generally considered mild.
The researchers say estrogen-depleting drugs, including aromatase inhibitors, have also been linked to an increased risk of joint pain and arthritis, but this link is controversial and requires further study.
SOURCES: Goss, P. Journal of the National Cancer Institute, Sept. 7, 2005; vol 97: pp 1262-1271. News release, Journal of the National Cancer Institute.