Estimation of medroxyprogesterone acetate against a human endometrial tumor constituted from the established Ishikawa cancer cells by a subrenal capsule assay]

In order to establish a sensitivity test system for the evaluation of anti-cancer hormonal agents, we tried a long-term subrenal capsule (SRC) assay, using nude mice with a transplanted solid tumor of endometrial cancer cells (Ishikawa's line). Unlike DNA-affecting agents, anti-cancer hormonal agents exert cytostatic effects rather than cytocidal effects, and their evaluation in a short period is considered to be inaccurate. Our test system is somewhat difficult in terms of technique, but it is useful since it can (1) evaluate the agents in the relatively short period of 28 days and (2) compare the cytostatic anti-tumor efficacy of two or more agents under the same conditions. The rate of successful tumor transplantation in nude mice in our system is very high, i.e., more than 90%. Although there are some points which need improvement, our system is considered to be useful as an assay system for the development of anti-cancer hormonal agents and other similar chemotherapeutic agents for cancers. When medroxyprogesterone acetate (MPA) was evaluated by means of this system, the administration period, as well as the dosage, was found to be important.