[Megestrol acetate in various doses in the treatment of metastatic breast carcinoma--clinical and endocrinologic studies].

Both medroxyprogesterone acetate (MPA) and megestrol acetate (MA) are effective in the treatment of metastatic breast cancer. Although the dose-dependent mode of actions of MPA have been extensively clarified, there is still some uncertainty regarding the mode of actions and dosage of MA. Thirty-three patients with metastatic breast cancer were treated with various dosages of MA under a phase-II study. Eight patients were given 200 mg, 9 X 400 mg, 10 X 600 mg and 6 X 800 mg MA daily per os. The LH, FSH, TBI, T3, T4, TSH, ACTH, aldosterone, testosterone, prolactin and cortisol levels were determined regularly during treatment to enable the investigation of the pharmacodynamics of MA. A complete remission was achieved in two patients, a partial remission in seven patients and there was no change in eight patients (total responder rate 51.5%). The clinical and endocrine changes therefore suggest that the dose-dependent mode of actions of MPA and MA are identical. Equivalent dosages of MPA are 1000-1500 mg per os and of MA 160-200 mg. Furthermore, similar relationships between the endocrine changes and remission behaviour of MA and MPA have been observed. Persisting tumour remissions are inevitable under cortisol suppression and normal prolactin, aldosterone and ACTH levels.