Analgesic activity of medroxyprogesterone acetate (MAP) in cancer patients: an antiinflammatory mediated activity?

When we initially used high doses of MAP (greater than 500 mg/day/im or greater than 2000 mg/day p.o.) in advanced cases of breast cancer, we noticed that, even before objective remission became apparent, the treatment induced subjective remission and a strong analgesic effect. Overall, our breast cancer patients treated with MAP at high doses (300 patients) showed a 65% incidence of pain relief. The analgesic effect of MAP does not seem to be closely related to its antitumour effect, because the same effect was also observed in patients with hormone-insensitive tumours. Our pharmacokinetic studies have demonstrated that it is important to use high doses in order to obtain high plasma levels. In order to clarify the mode of action of this MAP analgesy, hot-plate, tail-flick, Randall, writhing and carrageenin-oedema tests were carried out on rats. We found no evidence for central or peripheral analgesic activity, but there was evidence for an antiinflammatory activity of MAP.