The final analysis of survival data from the Comparison of Faslodex in Recurrent or Metastatic Breast Cancer (CONFIRM) trial is encouraging. Researchers confirmed what was seen as a trend in their initial secondary analysis: postmenopausal women with metastatic, hormone-positive breast cancer lived longer when given twice the past standard amount of fulvestrant (Faslodex).
Postmenopausal women are those who no longer have their periods because of age, anti-estrogen treatments or surgery.
In 2002, the FDA approved 250mg of fulvestrant for treating metastatic, hormone-positive breast cancer that grew or spread after use of another anti-estrogen medicine, such as tamoxifen. Results from past studies implied that the cancer might respond differently to fulvestrant depending on the dose given, so researchers designed CONFIRM to compare the effects of 250mg versus 500mg.
In September 2010, the FDA granted approval of 500mg of fulvestrant to treat the disease. They made the decision based on early results of CONFIRM suggesting treatment with 500mg led to longer progression-free survival, the time from the start of treatment until the cancer grew or spread. The higher dose was found just as safe as the standard.
At the time of the initial analysis, researchers also saw a trend toward increased overall survival in the group receiving 500mg of fulvestrant. Overall survival is the time from the start of treatment to death from any cause. In this study, OS was measured as median overall survival. This means, the number of months reported is the number of months that at least half of the women in that trial group lived.
The final results of CONFIRM report on OS at a later point — after 75 percent of trial participants passed away. The finding that double the past standard dose of fulvestrant is superior would be strengthened if an increase in OS rates also was seen at this later point among those given 500mg of the medicine.
The study was blind, meaning no participant or doctor knew which treatment was being given. Trials are often blinded to prevent anyone from reporting or believing they feel better or worse because of the treatment they are being given.
In total, 736 women were randomly assigned to one of two treatment groups:
- 500mg fulvestrant given as two shots into the muscle at the start of the trial and on days 14, 28 and every 28 days thereafter
- 250mg fulvestrant given as a shot into the muscle followed by a shot of a placebo at the start of the trial; placebo given by shot twice on day 14; and 250mg fulvestrant given by shot plus placebo given by shot every 28 days thereafter
The researchers collected data on overall survival and serious side effects. Placebo is an inactive substance.
The data showed
- half of the women in the 250mg group were alive at 22.3 months
- half of the women in the 500mg group were alive at 26.4 months
- both doses of fulvestrant were similarly safe
What This Means for You
Though the 500mg dose of fulvestrant was already approved for treating metastatic, hormone-positive breast cancer that grew or spread after treatment with another anti-estrogen medicine, the final analysis of this trial confirms the findings on which FDA approval was based.
Positive results like these may prompt researchers to explore whether fulvestrant can be used as a first-line therapy, or the first medicine given to treat metastatic, hormone-positive disease. Currently, the standard of care is to give aromatase inhibitors as first-line therapy. One study, called FALCON, is already exploring this.
If you have metastatic, hormone-positive breast cancer and are postmenopausal, talk with your doctor about these findings. It is OK to ask why your doctor recommends a certain medicine or dosage. If you have questions, don’t be afraid to speak up.
To learn more about medicines for hormone-positive breast cancers, read our Guide to Understanding Hormonal Therapy.
To learn more about metastatic breast cancer, read Metastatic Breast Cancer Series: Guide for the Newly Diagnosed.
Di Leo, A, Jerusalem, G, Pertuzelka, L, Torres, R, Bondarenko, I, et al. Final overall survival: Fulvestrant 500mg vs 250mg in the randomized CONFIRM trial. Journal of the National Cancer Institute. 2014; 106 (1).