When (if ever) would you use fulvestrant up-front instead of an aromatase inhibitor for ER+ or PR+ metastatic breast cancer?  

There are 2 scenarios based on the data and clinical guidelines that one can consider fulvestrant as 1st line therapy for ER+ metastatic breast cancer. Denovo or treatment naive stage 4 patients with bone only mets did better on fulvestrant vs an AI in the FALCON trial. SWOG 0226 showed a survival b...

Fulvestrant is probably as good or better than AI therapy in the first line setting but has less evidence. It's also less convenient with requirement of monthly injections. The situation that comes up most frequently in my practice is if a patient develops metastatic disease while on adjuvant AI or ...

I often use combination anastrozole and fulvestrant in endocrine naive patients given a relative 26% overall survival advantage compared to anastrozole alone, or in patients who relapsed >10 years after initial diagnosis (irrespective of prior endocrine treatment), given about a relative 40% prog...

The key question is whether there is an advantage for using an AI with fulvestrant upfront, and although S0226 noted that there was, the follow-up PK study from S0226 showed a significantly lower anastrazole levels in the combination arm throughout the treatment course (Hertz, Br J Clinical pharm 20...