Principles of chemoradiation: theoretical and practical considerations.

Chemotherapy agents known to enhance the effects of radiation in preclinical studies have been used concurrently with radiotherapy in numerous clinical trials with the prospect of further enhancing radiation-induced local tumor control. While some success in several tumor histologies has been achieved using this approach, a major concern has been enhancement in normal tissue toxicity. This brief review addresses both theoretical and practical issues with respect to chemoradiation clinical trials. Recommendations for clinical trials are provided that, if implemented, can increase our understanding of basic mechanisms (in patients) and provide a more rational approach for future trials.