Response to medroxyprogesterone acetate (NSC-26386) as secondary hormone therapy for metastatic breast cancer in postmenopausal women

by Selleckchem | Mar 24 2023

We have treated 40 postmenopausal women with documented metastatic breast cancer with medroxyprogesterone acetate. The average age was 63 years and the patients were, on the average, 14 years' postmenopausal. Only two patients had received no prior additive hormone therapy. The remainder had previously received estrogen, androgens, or both. Only two patients had objective evidence of tumor regression. In one patient a metastatic node disappeared for 7+ months, and the other patient had well-documented clinical improvement and control of brain mestastases for 22 months. Two other patients had mixed responses of chest wall metastases (regression of some but not all lesions), lasting 3 and 4 months respectively. Five other patients had obvious subjective benefit. There were four objective responses (10%) and five subjective responses (12%). There was no correlation between route of administration and response. All patients receiving benefit had previously responded to other hormones. Side effects were usually absent or consisted of mild fluid retention; however, four patients had disease stimulation from therapy.

PIP: 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.

Comments：

This study evaluated the use of medroxyprogesterone acetate (MPA) in treating metastatic breast cancer in 40 postmenopausal women who have either not responded to or have relapsed after therapy with estrogens and androgens. The patients were evaluated after 6 weeks of therapy, and the criteria for evaluating response were those used by the Eastern Cooperative Oncology Group. The overall response rate was 22%, with 4 objective responses (10%) and 5 subjective responses (12%). The study found that MPA therapy is costly and of minimal usefulness as secondary therapy in metastatic breast cancer, and further studies should focus on megestrol and norethisterone acetate which have been documented to have better response rates.