Thermal dose and secondary tumour cell death

Both primary and secondary tumour cell death may occur in clinical hyperthermia. The equation usually used for calculation of thermal dose takes only the primary cell death into consideration. We propose that the thermal dose equation should be reassessed; contributions from secondary cell death should also be included. The secondary cell death is governed mainly by the temperature distribution during treatment, the arteriolar density distribution in the tumour and the heat sensitivity of the arterioles. Increased thermal dose and hence increased tumour treatment response may result if hyperthermic treatments are designed to maximize the secondary cell death. Massive secondary cell death may be achieved by inducing hot spots in tumour areas with high arteriolar density, identified in pretreatment tumour angiograms.