DOES VARIATION IN THE INVITRO CELLULAR RADIOSENSITIVITY EXPLAIN THE SHALLOW CLINICAL DOSE CONTROL CURVE FOR MALIGNANT-MELANOMA

In radiotherapy, clinical dose - control curves are generally more shallow than what should be expected from in vitro dose - survival curves for human cells of the same histology. One possible explanation is that a considerable inter-tumor heterogeneity in radiosensitivity flattens out the presumably steep individual dose - control curves. This paper compares dose - control curves for malignant melanomas derived from clinical data with curves derived from in vitro cell-survival experiments. Although inter-tumour variability in the in vitro dose and fractionation sensitivity may explain parts of the discrepancy between the steepness of clinical and in vitro dose - control curves, the present calculation indicates that a considerable additional variability, undetected by current in vitro assays, must be assumed to exist in order to resolve the discrepancy. © 1990 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted.