[Location, classification of histological subtype and rate of lung metastasis in radioactive phosphorus induced rat osteosarcoma: special reference to relation of dosage].

Radioactive phosphorus (P-32) was administered intraperitoneally to Wistar female rats at 2-week intervals. P-32 was administered at a total dose of 3 mCi (a single dose of 200 microCi, 15 times) to Group 1, 2.4 mCi (1 microCi/g body weight, 15 times) to Group 2, and 1.4 mCi (1 microCi/g, 10 times) to Group 3. Osteosarcoma was induced in 29 out of 80 rats (36%) in Group 1, 28 out of 40 (70%) in Group 2, and 31 out of 40 (78%) in Group 3. Bone tumor was predominant in the trunk (spine, ilium etc.) in Group 1 (86%), and in the extremities (femur, tibia etc.) in Group 2 (64%) and Group 3 (71%). Histological findings revealed neoplastic osteoid formation in all lesions. Osteoblastic type developed more in Group 1 than in Group 3, and fibroblastic type developed more in Group 3 than in Group 1. The rate of lung metastasis was significantly higher in Group 3 (94%) than in Group 1 (21%, p less than 0.01) or Group 2 (72%, p less than 0.05). This experimental method, especially that used for Group 3, appears to be useful for studying the basis of human osteosarcoma.