Combined drug-radiation treatments: indications and clinical problems.

The combined use of drugs and radiation in the treatment of cancer in man is reviewed. In most studies the combined result cannot be demonstrated to show more than an additive effect of the individual treatments. This may result in no more than an increase in toxicity and lack of gain. In others, therapeutic synergism is demonstrated by a spatial co-operation between the modalities. The critical questions concerning combined modality treatments are indicated and discussed, with particular reference to bleomycin. It is concluded that more careful randomised clinical trials with appropriately defined endpoints are required.