[Progestational agents and bone metastasis in breast cancer]

Hormonotherapy in metastatic breast cancer is actually performed using 3 therapeutic classes: antiestrogen as tamoxifen (TAM), progestins, megestrol acetate (MA) and medroxyprogesterone acetate (MPA), aromatase-inhibitors as aminoglutethimide (AG). We investigated therapeutic efficacy of progestins compared to other hormonotherapies in case of breast cancer with bone metastasis. In a literature review, we found ten randomized trials comparing: MPA versus AG, MPA versus MA, MPA versus TAM, MA versus AG versus TAM. The results show an advantage on the response rate using MPA; the usual dose was 900-2,000 mg daily. MPA mode of action can explain these results since they combine gestagenic, androgenics and glucocorticoid effects.