Phase III study of letrozole versus tamoxifen as first-line therapy of advanced breast cancer in postmenopausal women: analysis of survival and update of efficacy from the International Letrozole Breast Cancer Group.

PURPOSE: To analyze overall survival (OS) and update efficacy data for letrozole versus tamoxifen as first-line therapy in postmenopausal women with locally advanced or metastatic breast cancer. PATIENTS AND METHODS: This multicenter phase III trial randomly assigned 916 patients with hormone receptor-positive or unknown tumors letrozole 2.5 mg (n = 458) or tamoxifen 20 mg (n = 458) daily until disease progression. Optional cross-over was permitted at the treating physician's discretion. This report updates efficacy at a median follow-up of 32 months. RESULTS: The superiority of letrozole to tamoxifen was confirmed for time to progression (median, 9.4 v 6.0 months, respectively; P <.0001), time to treatment failure (median, 9 v 5.7 months, respectively; P <.0001), overall objective response rate (32% v 21%, respectively; P =.0002), and overall clinical benefit. Median OS was slightly prolonged for the randomized letrozole arm (34 v 30 months, respectively). Although this difference in OS is not significant, survival was improved in the randomized letrozole arm over the first 2 years of the study. Approximately one half of the patients in each arm crossed over. Total duration of endocrine therapy ("time to chemotherapy") was significantly longer (P =.005) for patients initially on letrozole (median, 16 months) than for patients initially on tamoxifen (median, 9 months). Time to worsening of Karnofsky performance score was significantly delayed with letrozole compared with tamoxifen (P =.001). CONCLUSION: This study documents the superiority of letrozole over tamoxifen in first-line endocrine therapy in postmenopausal women with advanced breast cancer.

Fulvestrant (Faslodex) in advanced breast cancer: clinical experience from a Belgian cooperative study.

Fulvestrant (Faslodex) is a new estrogen receptor (ER) antagonist with no agonist effects that is licensed for the treatment of postmenopausal women with hormone-sensitive advanced breast cancer (ABC) who have progressed/recurred on prior antiestrogen therapy. The Faslodex Compassionate Use Program (CUP) provides expanded access to fulvestrant in countries where it is not yet available for patients who are not eligible to enter clinical trials. This analysis pools data from 402 patients who received fulvestrant as part of the CUP in Belgium, predominantly as 3rd- to 5th-line endocrine therapy for ABC. Two patients experienced partial responses and 118 experienced stable disease lasting>or=6 months, resulting in an overall clinical benefit rate of 29.9%. Fulvestrant was active in patients with multiple sites of metastases, visceral metastases, human epidermal growth factor receptor 2-positive disease and after heavy endocrine pre-treatment. Fulvestrant was well tolerated, with only six patients (1.5%) discontinuing treatment following adverse events. These data support the findings of previous CUP analyses and Phase II and III trials, suggesting that fulvestrant is a valuable addition to the treatment sequence for postmenopausal women with ABC who have progressed/recurred on prior endocrine therapy.