| Abstract: | Sixty-one female SD rats with 7, 12-dimethylbenz(a) anthracene (DMBA)-induced mammary cancer were divided into six groups according to the antitumor agent administered: MPA (20 mg/kg, Im), FT 207 (40 mg/kg, Ip), MPA (20 mg/kg, Im) + FT 207 (40 mg/kg, Ip), E2 priming (3 micrograms/body, Im, three days) + MPA (20 mg/kg, Im), E2 (3 mg/body, Im, three days) + MPA (20 mg/kg, Im) and control. The sizes of the tumors in all DMBA rats were measured at 1, 2, 3 and 4 weeks after the start of the administration, and the antitumor effects were compared among the groups. The antitumor effect of MPA + FT 207 was better than that when they were administered separately. It was shown that chemo-endocrine therapy with MPA was very effective. The antitumor effect was in the order of E2 priming + MPA, E2 + MPA and MPA among these three groups. E2 priming before MPA administration was thought to be very promising. The progesterone receptor (PgR) level tended to increase by E2 priming in DMBA tumors. Furthermore, in the E2 priming + MPA group, the tumors with high PgR levels before therapy tended to be more responsive than those with low PgR levels. |
