(ChemotherapyAdvisor) – Postmenopausal women with previously untreated hormone-receptor–positive metastatic breast cancer who received a combination of anastrozole and fulvestrant had significantly longer progression-free survival (PFS) than with anastrozole alone or sequential anastrozole and fulvestrant, a study in the New England Journal of Medicine August 2, 2012, reported.

A total of 707 women were randomly assigned to oral anastrozole 1mg/day—with patients encouraged to cross over to fulvestrant alone if disease progressed—or the combination of anastrozole and fulvestrant 500mg IM day 1 and 250mg days 14 and 28 and then monthly.

At a median follow-up of 35 months for patients without disease progression or death, median PFS, the primary outcome, was 13.5 months in the anastrozole alone group vs 15.0 months for the combination arm (HR 0.80 [95% CI 0.68–0.94]; log-rank P=0.007).

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Median overall survival was 41.3 months in the anastrozole alone arm and 47.7 months in the combination arm (HR 0.81 [95% CI, 0.65–1.00; log-rank P=0.05), despite the fact that 143 patients (41.4%) in the anastrozole alone arm crossed over to fulvestrant following disease progression, Rita S. Mehta, MD, of the University of California Irvine Medical Center, Chao Family Comprehensive Cancer Center, Orange, CA, and colleagues noted. Those who did not cross over received chemotherapy.

A posthoc analysis suggested “that the benefit provided by the combination therapy was the delay in disease progression,” they wrote.

“The results of our study suggest that trials of adjuvant therapy should be performed in which the combination of an aromatase inhibitor and high-dose fulvestrant is compared with an aromatase inhibitor alone or high-dose fulvestrant alone, in patients with estrogen-receptor–positive tumors for whom chemotherapy is not necessary,” they concluded.