Combination Anastrozole and Fulvestrant more effective than Anastrozole monotherapy for metastatic breast cancer

by Bruce Sylvester – taken from The New England Journal of Medicine (NEJM) –

Women treated with anastrozole and fulvestrant combination therapy have achieved over 6 months median increased survival time in hormone receptor-positive metastatic breast cancer compared to women treated with standard anastrozole monotherapy (47.7 months vs 41.3 months).

“The combination offers a new standard for first-line treatment of postmenopausal women with hormone receptor-positive metastatic breast cancer,” said lead investigator on the study Rita Mehta, M.D., of the University of California, Irvine Medical Center, Irvine California. “It has been many years since these patients have seen a new treatment that can significantly extend their overall survival time.”

Researchers from the SWOG S0226 trial reported this finding on August 2, 2012 in the New England Journal of Medicine.

They also reported that combination therapy increased median time to disease progression (15 months vs 13.5 months).

As background, the authors noted that anastrozole (Arimidex®) and fulvestrant (Faslodex®) are currently FDA-approved and used to treat breast cancer, but not in combination. Anastrozole suppresses tumor-promoting estrogen, and fulvestrant  blocks estrogen receptors and accelerates the degradation of these receptors.

Mehta and colleagues hypothesized that these two different modes of action might become synergistic in combination therapy against hormone receptor-positive breast cancer, which appears in more than one half of all cases of breast cancer.

The investigators also reported that 41 percent of patients on the anastrozole-only arm switched to fulvestrant treatment after their disease progressed on anastrozole, suggesting that combined use of the two agents not sequential use elicited the results.