ADDITIVITY OF HYPOXIC CELL SENSITIZERS IN CLINICAL PRACTICE

Chemical hypoxic cell radiosensitizers will not increase the radiation damage to normal tissues at oxygen tensions similar to that of venous blood. They will, however, sensitize any normal tissues or cells at reduced oxygen tensions and the clinician should be aware of which tissues are at risk in this respect. In pratice, adding sensitizers to each other at the low concentrations that are necessary in clinical practice (because of toxicity) may increase in clinical enhancement ratio, but not beyond a value of about 1.7. Nevertheless, if the toxic effects are not additive, this could be of clinical benefit.