Response to medroxyprogesterone acetate (NSC-26386) as secondary hormone therapy for metastatic breast cancer in postmenopausal women
Klaassen, D.J.; Rapp, E.F.; Hirte, W.E.
Cancer Treatment Reports 60(3): 251-253
1976
ISSN/ISBN: 0361-5960 PMID: 1260780 Document Number: 460180
Progesterone, like estrogens, is used in the treatment of metastatic breast cancer. The 3 most active derivatives are megestrol, norethisterone acetate, and medroxyprogesterone acetate (MPA). This study evaluates the use of MPA in treating metastatic breast cancer in 40 postmenopausal women (average age, 63 years; average duration of postmenopause, 14 years) who have either not responded to or have relapsed after therapy with estrogens and androgens. 18 patients received a depot preparation of MPA intramuscularly in a loading dose of 3.2 g over a 2-week period and then 400 mg at 2-4 week intervals. 22 patients received the drug orally in a dose of 200 to 300 mg daily. Patients were evaluated after 6 weeks of therapy. Criteria for evaluating response were those used by the Eastern Cooperative Oncology Group. Only 2 of 40 patients exhibited an objective response (disappearance of metastatic lymph node for 9 months in 1 and well-documented clinical improvement and control of brain metastases for 22 months in another). 2 patients had mixed responses of chest wall metastases (regression of some but not all lesions) lasting 3 and 4 months respectively. 5 patients had obvious subjective response (pain relief) but no objective response. Overall response rate was 22%: 4 objective responses (10%) and 5 subjectives responses (12%). Route of administration did not correlate with response. Tumor stimulation and clinical deterioration occurred in 4 patients. It appears that MPA therapy is costly and of minimal usefulness as secondary therapy in metastatic breast cancer. Further studies should focus on megestrol and norethisterone acetate which have been documented to have better response rates.