A 500-mg dose of fulvestrant improved survival compared with a 250-mg dose in women with estrogen receptor–positive (ER+) metastatic breast cancer with no increase in toxicity, according to an update of the Comparison of Faslodex in Recurrent or Metastatic Breast Cancer (CONFIRM) trial.
“For postmenopausal women with recurrent or progressing ER+ locally advanced or metastatic breast cancer for whom fulvestrant is appropriate, the standard of care has been 250 mg. Our results indicate that this should be modified to a 500-mg dose,” said lead author Angelo Di Leo, MD, PhD, head of the department of medical oncology at the Hospital of Prato, Istituto Toscano Tumoria, Prato, Italy.
CONFIRM was a double-blind, parallel-group, multicenter, phase 3 trial that randomized 736 women from 128 centers in 17 countries to receive either 250 mg or 500 mg of fulvestrant. Women were observed until 75% of the patients died; at the time of analysis, 554 died, 63 were lost to follow-up, and 16 withdrew consent.
The 500-mg dose achieved a clinically relevant 4.1-month difference in median overall survival compared with a 250-mg dose: 26.4 months and 22.3 months, respectively. The relative risk reduction in death was 19% for those taking the higher dose of fulvestrant.
Serious adverse events were reported in 8.9% of the 500-mg dose group and 6.7% of those receiving the lower dose.