Fulvestrant Superior to Anastrozole for HR-positive Advanced Breast Cancer

Among patients with previously untreated hormone receptor (HR)-positive, locally-advanced or metastatic breast cancer, endocrine therapy with fulvestrant significantly prolonged progression-free survival compared with anastrozole, according to a study published in The Lancet.¹

Aromatase inhibitors are a standard of care for women with HR-positive, locally advanced or metastatic breast cancer, though it is unclear whether 1 treatment option is superior to another.

Researchers investigated whether fulvestrant, a selective estrogen receptor degrader, could improve progression-free survival compared with anastrozole, a third-generation aromatase inhibitor, among postmenopausal patients who had not received prior endocrine therapy.

For the international, double-blind, phase 3 FALCON study (ClinicalTrials.gov Identifier: NCT01602380), researchers enrolled 462 patients with histologically confirmed estrogen receptor-positive or progesterone receptor-positive, or both, locally advanced or metastatic breast cancer. Participants were randomly assigned 1:1 to receive fulvestrant intramuscular injections or oral anastrozole.

Treatment with fulvestrant significantly reduced the risk of progression or death by nearly 20% compared with anastrozole (hazard ratio, 0.797; 95% CI, 0.637-0.999; P = .0486).

Median progression-free survival was 16.6 months (95% CI, 13.83-20.99) in the fulvestrant arm vs 13.8 months (95% CI, 11.99-16.56) in the anastrozole arm.

The most common adverse events were arthralgia and hot flushes. Seven percent of patients in the fulvestrant group discontinued treatment due to adverse events compared with 5% of those treated with anastrozole.

The findings support the use of fulvestrant as a standard of care for first-line treatment of postmenopausal women with HR-positive advanced breast cancer who have not received previous endocrine therapy.

Reference

1. Robertson JF, Bondarenko IM, Trishkina E, et al. Fulvestrant 500 mg versus anastrozole 1 mg for hormone receptor-positive advanced breast cancer (FALCON): an international, randomised, double-blind, phase 3 trial. Lancet. 2016 Nov 28. doi: 10.1016/S0140-6736(16)32389-3 [Epub ahead of print]