Residual DNA double strand breaks in perfused but not in unperfused areas determine different radiosensitivity of tumours

The dose-response of residual γH2AX foci is highly dependent on tumour cell oxygenation in well perfused areas. This dependence decreases further away from tumour vessels. Only γH2AX evaluation in perfused tumour areas can distinguish between the different radiocurability of the two tumour models.