(HealthDay News) — The combination of anastrozole and fulvestrant improves survival in patients with hormone receptor-positive metastatic breast cancer, according to a study published in the Aug. 2 issue of the New England Journal of Medicine.
Rita S. Mehta, M.D., from the University of California Irvine Medical Center in Orange, and colleagues randomly assigned postmenopausal women with previously untreated hormone receptor-positive metastatic breast cancer to receive either 1 mg of anastrozole orally every day (group 1), with crossover to fulvestrant alone strongly encouraged if the disease progressed, or to a combination of anastrozole and fulvestrant (group 2) in a 1:1 ratio.
The researchers found that the median progression-free survival was 13.5 months in group 1 and 15.0 months in group 2 (hazard ratio [HR] for progression or death with combination therapy, 0.80; P = 0.007 by the log-rank test). In all subgroups the combination therapy was more effective than anastrozole alone, with no significant interactions. Despite the fact that 41 percent of the patients in group 1 crossed over to fulvestrant after progression, overall survival was longer with combination therapy (median, 41.3 months in group 1 versus 47.7 months in group 2; HR for death, 0.81; P = 0.05 by the log-rank test). In group 2 there were three deaths possibly associated with treatment. There was no significant difference in the rates of grade 3 to 5 toxic effects between the groups.
“The combination of anastrozole and fulvestrant was superior to anastrozole alone or sequential anastrozole and fulvestrant for the treatment of hormone receptor-positive metastatic breast cancer, despite the use of a dose of fulvestrant that was below the current standard,” the authors write.
The study was partially funded by AstraZeneca, which manufactures anastrozole and fulvestrant; several authors disclosed financial ties to pharmaceutical companies, including AstraZeneca.