Tumour reoxygenation during fractionated radiotherapy; studies with a transplantable mouse osteosarcoma
article
The oxygenation status of transplantable mouse osteosarcoma C22LR was studied from the radiation dose survival curves. Cell suspensions were prepared from this tumour and the radiosensitivity of both the suspensions in vitro and the tumour in situ were determined by the endpoint dilution assay of Hewitt. From these survival curves, the mean anoxic cell fraction in the tumour in situ could be determined at 14%. After four daily doses of 250 rad to the tumour, the anoxic cell fraction rose to 32% and two days after a single dose of 1000 rad 88% anoxic cells were found. A calculation of the fractions of surviving cells shows that little or no reoxygenation of previously anoxic cells had occurred in this tumour after the preferential elimination of oxygenated cells by the radiation. This contrasts markedly with earlier observations for another tumour and it seems likely that different tumours may differ greatly in their capacity to reoxygenate anoxic cells during fractionated therapy. Since this capacity was calculated to be most important in determining the radiation dose needed to cure a tumour, a difference in reoxygenation may well be responsible for a large part of the variation in curability by radiotherapy between different tumours. © 1968.
Topics
TNO Identifier
227037
ISSN
00142964
Source
European Journal of Cancer, 4(2), pp. 173-182.
Pages
173-182
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