Radiation response of "clonogenic" tumor cell release from NFSA2ALM1 tumors.

A newly developed "clonogenic" tumor cell release assay was applied to a transplantable spontaneous mouse fibrosarcoma, NFSA2ALM1 , growing in the leg. The tumors 32 days after transplantation (3400 mm3) released 36 "clonogenic" tumor cells per hour into the blood circulation. After irradiation of the leg tumors, the "clonogenic" tumor cell release rate declined in 1 day to a minimum, and remained low during the following several days. The dose-response curve for the "clonogenic" tumor cell release determined 1 day after local irradiation of the tumors showed a D0 of 3.8 Gy.