The effect of treatment with 4-hydroxyandrostenedione or medroxyprogesterone acetate on human breast tumour regression.

We have assessed cell deletion in breast tumours removed surgically from postmenopausal women by measuring the distribution ratio of acid phosphatase activity between the bound (in the lysosome) and free (in the phagosome) states. In benign breast tumours the acid phosphatase distribution ratio was much higher than that found in untreated malignant breast tumours. The acid phosphatase distribution ratio was also measured before and after treatment in malignant breast tumours removed from eight patients treated with 4-hydroxyandrostenedione (4-OH A) and in six patients treated with medroxyprogesterone acetate (MPA). Elevated acid phosphatase distribution ratios in benign compared with malignant tumours, and in malignant tumours after treatment from four of eight patients treated with 4-OH A and from three of six patients treated with MPA, may suggest higher cell deletion in these patients.