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Clinical overview of anastrozole--a new selective oral aromatase inhibitor
1Gynaecology and Obstetrics Clinic, University of Kiel, Germany.
Abstract:
The efficacy and tolerability of the new selective aromatase inhibitor, anastrozole (Arimidex), was compared with megestrol acetate in the treatment of advanced breast cancer in postmenopausal women. In two independent prospective randomised trials, patients who progressed after prior tamoxifen therapy received anastrozole 1 or 10 mg once daily, or megestrol acetate, 40 mg q.i.d. The two studies were designed to allow the data to be combined to increase the statistical power of the analyses. It is the data from these combined analyses that are considered in further detail. After 6 months of follow-up, the proportion of patients gaining clinical benefit (complete response + partial response + stable disease > or = 24 weeks) was approximately one third of patients in all three groups. No significant difference was observed between either dose of anastrozole and megestrol acetate in the time to disease progression (130-153 days). All three treatments were generally well tolerated, but significantly more patients on megestrol acetate gained weight, and the weight gain in this group continued up to at least 9 months of follow-up. At a 12-month update of tolerability, of the commonly observed adverse events, a greater than 2-fold difference between treatment arms was observed for hypertension, weight gain, dyspnoea, vaginal haemorrhage, sweating and diarrhoea (all higher on megestrol acetate except for diarrhoea). Anastrozole is effective and well tolerated and on the basis of these data, 1 mg once daily is the recommended clinical dose in postmenopausal women with advanced breast cancer.
Insights
Anastrozole (Arimidex) and megestrol acetate showed similar efficacy in treating advanced breast cancer in postmenopausal women. Anastrozole, particularly at 1 mg daily, was better tolerated, with less weight gain and fewer adverse events.
Area of Science:
- Oncology
- Endocrinology
- Pharmacology
Background:
- Advanced breast cancer in postmenopausal women is a significant clinical challenge.
- Selective aromatase inhibitors represent a newer therapeutic option compared to progestins like megestrol acetate.
Purpose of the Study:
- To compare the efficacy and tolerability of anastrozole (Arimidex) versus megestrol acetate in postmenopausal women with advanced breast cancer.
- To determine the optimal clinical dose of anastrozole for this patient population.
Main Methods:
- Two independent prospective randomized trials combined data for increased statistical power.
- Patients with advanced breast cancer who progressed after tamoxifen therapy were randomized.
- Treatments included anastrozole (1 mg or 10 mg daily) or megestrol acetate (40 mg q.i.d.).
Main Results:
- Clinical benefit (response or stable disease >= 24 weeks) was observed in approximately one-third of patients across all treatment groups.
- No significant difference in time to disease progression between anastrozole and megestrol acetate.
- Anastrozole was better tolerated, with significantly less weight gain and fewer adverse events (hypertension, dyspnoea, vaginal haemorrhage, sweating) compared to megestrol acetate.
Conclusions:
- Anastrozole is an effective and well-tolerated treatment for advanced breast cancer in postmenopausal women.
- The recommended clinical dose of anastrozole is 1 mg once daily.
- Anastrozole offers a favorable tolerability profile compared to megestrol acetate, particularly regarding weight gain and other adverse events.