Women's Health

Femara Shown To Substantially Cut Risk of Breast Cancer Recurrence

By: Madeline Ellis
Published: Sunday, 23 March 2008
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Breast cancer kills 500,000 people worldwide every year. U.S. women have a one in eight lifetime chance of developing invasive breast cancer and a one in 35 chance of dying from breast cancer.

Most women with estrogen-sensitive cancers, which comprise 60 percent of breast cancers, undergo surgery followed by treatment with Tamoxifen, a drug which reduces breast cancer recurrence by shielding breast cells from the harmful effects of estrogen. However, the benefits of the drug drop significantly and the risk of negative side effects tend to increase after five years. Patients are often taken off Tamoxifen and placed on another class of breast cancer drugs called aromatase inhibitors (AI), that work by decreasing the body’s actual production of estrogen.

Until recently, it was believed that an AI was only useful when started almost immediately after the patient stopped using Tamoxifen. In fact, the Food and Drug Administration (FDA) approved it only for within a three-month window. However, a new study shows that even women who didn’t start an AI right away still benefit from it, even if they start it years later.

The study, which appears in the Journal of Clinical Oncology, involved 5,187 women who had undergone Tamoxifen treatment following the diagnosis of estrogen receptor-positive breast cancer and lasted five years. In the trial, 2,383 women took placebos and the remainder received an aromatase inhibitor known as letrozole and marketed under the name of Femara.

The study found that women who began Femara beyond the three-month window cut the risk of breast cancer recurrence by almost 60 percent, from nearly five to two percent. The risk of death from breast cancer was cut by 50 percent. The spread of cancer, metastasis, was reduced by 61 percent, and new cancer in the other breast was reduced by more than 80 percent.

The study also found that the benefits were seen even when women initiated the drug one to seven years after they stopped treatment with tamoxifen.

Lead researcher, Dr. Paul E. Goss, director of Breast Cancer Research at Massachusetts General Hospital Cancer Center in Boston said, “We were expecting letrozole to work from the earlier, initial results, but the actual magnitude of benefit was a bit surprising. For any woman who has had hormone-sensitive breast cancer in the past, our results show a big reduction in recurrence if letrozole is initiated any time between one and seven years after five years of tamoxifen. That is up to 12 years after diagnosis.”

A second study conducted by Hyman Muss of the University of Vermont supported Dr. Goss’s findings. Muss found that letrozole was effective in reducing the recurrence risk for women of all ages, including those over 70. This study was also published in the Journal of Clinical Oncology.

The researchers said there was one slight down side to letrozole therapy; just over five percent of the 1,500 women taking the drug reported a new diagnosis of osteoporosis or bone fracture, compared to about three percent of 800 study participants who were not on the regimen.

Dr. Goss said the findings of the study are expected to be applied immediately to receptor-positive breast cancer treatment. And although the study looked at the effects of letrozole only, the results will likely apply to all aromatase inhibitors; exemestane manufactured by Pfizer, Inc. and sold under the brand Aromasin, and anastrozole made by AstraZeneca Plc, sold under the brand Arimidex.

Dr. Goss said that, based on the new findings, “we believe every patient who has previously taken tamoxifen should discuss the findings of this study with her oncologist. Our results suggest if you take anti-estrogen, aromatase inhibitor therapy at any point of diagnosis, it is going to impact your chances of not experiencing a recurrence.” Goss went on to say that, “There are probably hundreds of thousands of breast cancer patients around the world today who are in exactly this situation.”