Frontline Treatment of ER-Positive Breast Cancer

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The frontline regimen for postmenopausal patients with ER-positive, HER2-negative metastatic breast cancer has been studied extensively in recent years. In a case-based scenario, Adam Brufsky, MD, PhD, describes a patient who was treated with an aromatase inhibitor (AI) for 5 years and remained disease-free for 3 years before developing a number of bone metastases.

The combination of an AI with fulvestrant could be beneficial as a frontline treatment for some patients with ER-positive breast cancer, suggests Sara Hurvitz, MD. The FACT and SWOG 226 trials examined the efficacy of a combination of 250-mg fulvestrant plus anastrozole compared with anastrozole alone in the first-line setting. The FACT trial did not show a benefit with the combination while the SWOG 226 study demonstrated a 20% advantage in progression-free survival with the combination over the single-agent.

Despite these contradictory findings, the combination could offer a benefit for some patients, suggests Hurvitz. Previous studies used a smaller dose of fulvestrant than is currently approved. Studies are now assessing fulvestrant at the 500 mg dose in combination with AIs in the frontline setting, notes Hope S. Rugo, MD. Outside of this combination, nonsteroidal AI monotherapy is an acceptable option, Rugo suggests.

In the frontline setting for patients with metastatic breast cancer, fulvestrant could offer greater benefits and lower toxicity, Hurvitz suggests. The toxicity profile for fulvestrant is more favorable than an AI.