Improved microcirculation in irradiated tumours

Abstract

The response of the tumour micro-circulation of a mouse mammary tumour to fractionated irradiation was investiagted by the quantitative analysis of cinematographically recorded micro-angiograms made of tumours, growing in a sheet-like fashion with a thickness of about 50 μ. The results indicate that, during a course of fractionated radiotherapy with daily fractions of 576 rads, there is an improvement of the tumour microcirculation, which is most marked at the 7th treatment day when the tumours have just regressed beyond their initial size. The technique of growing sheet-like tumours in a modification of the Algire chamber system (called the “sandwich” system), does not only allow the direct observation, recording or measurement of the various aspects of the tumour microcirculation, but also permits direct estimation of the local oxygenation (redox) state of the tumour tissue by using micro-fluorometric methods. This work was undertaken while the author was on leave from the Radiobiological Institute TNO. It was supported by grant No. USPHS 2-02-CA-06519. Part of this work was presented at the symposium “Time and Dose Relationships in Radiation Biology as Applied to Radiotherapy”, held at Carmel, California, September 1969