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Response of fibrosarcoma cell subpopulations to small doses of radiation delivered in situ

Journal Article · · Int. J. Radiat. Oncol., Biol. Phys.; (United States)
The survival of cells from 2 tumor subpopulations after gamma-ray doses ranging from 1 to 19 Gy was determined using a lung colony assay. Methylcholanthrene-induced fibrosarcomas grown in the hind legs of C3H/Kam pathogen-free mice were irradiated in situ when the tumors were 8-10 mm in diameter. Single cell suspensions prepared from excised tumors were separated on a linear density gradient, and the clonogenicity of predominantly oxic Band 2 and predominantly hypoxic Band 4 cells was measured. The surviving fraction of cells after doses of 1, 2, and 3 Gy was estimated from that measured after total doses of 5 Gy, 10 Gy, and 15 Gy, under the assumption of equal effect per fraction. Very little curvature was evident in the survival curves of Band 2 and Band 4 cells. The initial segment of the survival curve of the predominantly oxic Band 2 cells was steeper than that of the predominantly hypoxic Band 4 cells; both remained linear over a large range, to doses in excess of 3 Gy. These results imply that these tumor subpopulations will be insensitive, in their response to multifractionated regimens, to changes in size of dose per fraction in the range 0 to 3 Gy, a trait shared by two acutely responding normal tissues (murine testis and jejunum).
Research Organization:
M.D. Anderson Hospital and Tumor Inst., Houston, TX
OSTI ID:
5586379
Journal Information:
Int. J. Radiat. Oncol., Biol. Phys.; (United States), Journal Name: Int. J. Radiat. Oncol., Biol. Phys.; (United States) Vol. 9:2; ISSN IOBPD
Country of Publication:
United States
Language:
English