Letrozole, a new oral aromatase inhibitor for advanced breast cancer : Double-blind randomized trial showing a dose effect and improved efficacy and tolerability compared with megestrol acetate

PURPOSETo compare two doses of letrozole and megestrol acetate (MA) as second-line therapy in postmenopausal women with advanced breast cancer previously treated with antiestrogens.PATIENTS AND METHODSFive hundred fifty-one patients with locally advanced, locoregionally recurrent or metastatic breast cancer were randomly assigned to receive letrozole 2.5 mg (n = 174), letrozole 0.5 mg (n = 188), or MA 160 mg (n = 189) once daily in a double-blind, multicenter trial. Data were analyzed for tumor response and safety variables up to 33 months of follow-up evaluation and for survival up to 45 months.RESULTSLetrozole 2.5 mg produced a significantly higher overall objective response rate (24%) compared with MA (16%; logistic regression, P = .04) or letrozole 0.5 mg (13%; P = .004). Duration of objective response was significantly longer for letrozole 2.5 mg compared with MA (Cox regression, P = .02). Letrozole 2.5 mg was significantly superior to MA and letrozole 0.5 mg in time to treatment failure (P = .04 and...