[Experimental study of combination medical endocrine therapy on DMBA-induced mammary tumor, with special reference to the effect of drug-dose on various factors].
Changes of various factors associated with the antitumor effect of medroxyprogesterone acetate (MPA) and tamoxifen (TAM) against the DMBA-induced mammary tumor in rats were studied. Tumor bearing SD rats were divided into control group and experimental groups, consisting of single therapy group and combination therapy groups; TAM----MPA (T----M) group and MPA----TAM (M----T) group. A much higher degree of suppression of tumor growth was observed in the combination groups than in the single group. A significant reduction of spleen weight was observed in all of the experimental groups. The reduction of ER-expression in mammary tumor was observed in MPA groups (M, T----M) and in TAM groups (T, M----T), whereas the reduction of PgR was seen in two kinds of combination groups. The serum level of luteinizing hormone was decreased in M, but not in the combination groups. No change was observed in the percentage of pan T, CD4+ and CD8+, T cell subsets, except Thy 1+T cell was decreased depending on the MPA dose. In the combination group, using high dose MPA, the reduction of the degree of inflammatory cell infiltration into the adenocarcinomatous foci was observed immunohistochemically. These findings indicate that the combination medical endocrine therapy for mammary tumor might be much more effective for the tumor regression than single use, without inducing any detectable side effects on either hormonal or immune systems, when a low dose of MPA less than 1.5 mg/100g B.W. was combined with TAM.
Kosaka
A
A
Division of Surgery, Shimizu City Hospital, Japan.
Yamashita
A
A
D015127:9,10-Dimethyl-1,2-benzanthracene; D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage*; D005260:Female; D008325:Mammary Neoplasms, Experimental / Q000139:chemically induced / Q000188:drug therapy* / Q000473:pathology; D008525:Medroxyprogesterone / Q000008:administration & dosage / Q000031:analogs & derivatives*; D017258:Medroxyprogesterone Acetate; D009929:Organ Size; D051381:Rats; D013629:Tamoxifen / Q000008:administration & dosage*
D000970:Antineoplastic Agents; D013629:Tamoxifen; D015127:9,10-Dimethyl-1,2-benzanthracene; D017258:Medroxyprogesterone Acetate; D008525:Medroxyprogesterone