(RxWiki News) Most breast cancers are fueled by the hormone estrogen, and a number of medications are made to block the production of estrogen. A recent trial assessed one such medication in treating advanced breast cancer.
This international trial found that women with advanced estrogen receptor-positive breast cancer who were given 500 mg of Faslodex (fulvestrant) lived longer than those who received 250 mg of the medication.
The medicine was well tolerated by the women in both groups, and there were no serious side effects or safety concerns, according to the researchers.
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Angelo Di Leo, MD, PhD, from the Medical Oncology Unit at the Hospital of Prato in Prato, Italy, led this study — the phase lll Comparison of Faslodex in Recurrent or Metastatic Breast Cancer (CONFIRM) trial, which involved women from 17 countries around the world.
Faslodex is part of a class of medications called anti-estrogens, which are effective in blocking the production of estrogen. The medication is used to treat estrogen-sensitive breast cancer in postmenopausal women. It works by blocking the activity of estrogen in breast tissue, which stops the cancer from growing.
The CONFIRM trial recruited 736 women with advanced or metastatic (had spread) estrogen receptor-positive breast cancer between 2005 and 2007. The median age of participants was 61.
Study members were randomly assigned to receive either 250 mg of Faslodex (374 women) or 500 mg of Faslodex (362 women), which is given by injection.
The first analysis of results was performed in 2009, at which time about 50 percent of the participants had died. The initial results indicated a trend suggesting that the 500 mg dosing was superior. The researchers decided to analyze results again after 75 percent of the study members had died.
The final analysis was performed in late 2011 when 554 women of the original 736 had died. The researchers analyzed overall survival.
Median overall survival for women who received 500 mg of Faslodex was 26.4 months, compared to 22.3 months for those who took 250 mg of the medicine.
Serious side effects known to be related to the treatment were experienced by 2.2 percent of the women in the the 500 mg group and 1.1 percent of those in the 250 mg group. Five participants in the 500 mg group died of serious adverse events as did four women in the 250 mg group.
“In patients with locally advanced or metastatic estrogen receptor–positive breast cancer, fulvestrant 500 mg is associated with a 19 percent reduction in risk of death and a 4.1-month difference in median [overall survival] compared with fulvestrant 250 mg. Fulvestrant 500 mg was well tolerated, and no new safety concerns were identified,” the researchers concluded.
Results from this trial were published December 19 in the Journal of the National Cancer Institute.
This study was designed and funded by AstraZeneca Pharmaceuticals, the maker of Faslodex.