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Background: The different pharmacokinetic profiles of the intramuscularly administered antioestrogen fulvestrant and oral endocrine treatments have led to speculation among some physicians that this could result in a delayed time to response (TTR) with fulvestrant., Patients and Methods: An analysis of TTR was performed on data from 2 phase III trials comparing fulvestrant and anastrozole as second-line treatments for postmenopausal women with advanced-stage, tamoxifen-resistant breast cancer., Results: In a combined analysis of the data from these trials, median TTR was 3.1 months (range, 0.9-33.1 months) for fulvestrant and 3 months (range, 0.7-20.2 months) for anastrozole, although responses were still being noted after 2-3 years of stable disease in some patients. Data were subsequently analyzed from 3 other randomized phase III trials of fulvestrant, anastrozole, and tamoxifen in postmenopausal women. Time to response was also similar between the 3 treatments in these additional analyses., Conclusion: Time to response is similar between fulvestrant and oral endocrine treatments, despite pharmacokinetic differences.

Background: Fulvestrant is an estrogen receptor antagonist with no agonist effects. In the second-line treatment of advanced breast carcinoma, fulvestrant was shown previously to be as effective as the third-generation aromatase inhibitor, anastrozole, in terms of time to disease progression and objective response rates. The authors reported the overall survival results from these studies., Methods: A prospectively planned, combined, overall survival analysis was performed, including data from two Phase III trials that compared the efficacy and tolerability of fulvestrant (250 mg monthly; n = 428) with anastrozole (1 mg daily; n = 423) in the treatment of postmenopausal women with advanced breast carcinoma who had disease progression after receipt of previous endocrine treatment., Results: At an extended median follow-up of 27.0 months (range, 0-66.9 months), 319 (74.5%) patients in the fulvestrant group and 322 (76.1%) patients in the anastrozole group had died. Prolonged survival was observed with both drugs, with 10-20% of patients still alive > 5 years after randomization. The median overall survival was similar between treatments, being 27.4 months and 27.7 months in fulvestrant and anastrozole-treated patients, respectively (hazards ratio, 0.98; 95% confidence interval, 0.84-1.15; P = 0.809). Fulvestrant continued to be well tolerated, and was associated with a significantly lower incidence of joint disorders compared with anastrozole (P = 0.0234)., Conclusions: The current analysis showed that fulvestrant was similar to anastrozole with respect to overall survival in the second-line treatment of postmenopausal women with advanced breast carcinoma.

The efficacy of fulvestrant (Faslodex), a novel oestrogen receptor (ER) antagonist that downregulates the ER and has no known agonist effects, was compared with the aromatase inhibitor anastrozole (Arimidex) for the second-line treatment of advanced breast cancer in postmenopausal women with visceral and non-visceral metastases. Assessment was by means of a retrospective subgroup analysis of combined data from two randomised, phase III trials. Objective response (OR) rates were similar in patients treated with fulvestrant and anastrozole, respectively (21.9% versus 19.3%-patients with no visceral metastases; 15.7% versus 13.2%-all of the patients with visceral metastases; 18.8% versus 14.0%-patients with visceral metastases only). The proportion of patients with clinical benefit (CB) was also similar between treatments and between subgroups with and without visceral disease. Fulvestrant is at least as effective as anastrozole, providing a valuable treatment option for advanced breast cancer in postmenopausal women with visceral metastases who have failed on prior endocrine therapy.

Purpose: To compare the efficacy and tolerability of fulvestrant (formerly ICI 182,780) with anastrozole in the treatment of advanced breast cancer in patients whose disease progresses on prior endocrine treatment., Patients and Methods: In this double-blind, double-dummy, parallel-group study, postmenopausal patients were randomized to receive either an intramuscular injection of fulvestrant 250 mg once monthly or a daily oral dose of anastrozole 1 mg. The primary end point was time to progression (TTP). Secondary end points included objective response (OR) rate, duration of response (DOR), and tolerability., Results: Patients (n = 400) were followed for a median period of 16.8 months. Fulvestrant was as effective as anastrozole in terms of TTP (hazard ratio, 0.92; 95.14% confidence interval [CI], 0.74 to 1.14; P =.43); median TTP was 5.4 months with fulvestrant and 3.4 months with anastrozole. OR rates were 17.5% with both treatments. Clinical benefit rates (complete response + partial response + stable disease > or = 24 weeks) were 42.2% for fulvestrant and 36.1% for anastrozole (95% CI, -4.00% to 16.41%; P =.26). In responding patients, median DOR (from randomization to progression) was 19.0 months for fulvestrant and 10.8 months for anastrozole. Using all patients, DOR was significantly greater for fulvestrant compared with anastrozole; the ratio of average response durations was 1.35 (95% CI, 1.10 to 1.67; P < 0.01). Both treatments were well tolerated., Conclusion: Fulvestrant was at least as effective as anastrozole, with efficacy end points slightly favoring fulvestrant. Fulvestrant represents an additional treatment option for postmenopausal women with advanced breast cancer whose disease progresses on tamoxifen therapy.