Treatment of cancer with radiation and drugs.

PURPOSE: To review the current status and future prospects of combined treatment of cancer with radiation and drugs. DESIGN: A review of (1) mechanisms whereby combined use of radiation and drugs might lead to improved therapeutic benefit for the treatment of cancer; (2) problems related to the design and analysis of clinical trials that evaluate combined modality treatment; and (3) clinical results of larger randomized trials that have compared combined versus single modality treatment for various types of cancer. RESULTS: Improvement in the therapeutic index depends on exploitation of the biologic properties that differ between tumors and normal tissues; such properties may include mechanisms of resistance to radiation and drugs, tissue microenvironment, and cell proliferation or repopulation during radiotherapy. To detect or rule out the small but clinically important differences in outcome that might occur will require the performance of large, randomized, controlled trials or patient-based meta-analyses; single-arm studies, small randomized trials, and subgroup analyses of larger trials can generate hypotheses. Clinical gains from combined treatment have been demonstrated in a few sites, with disappointing results in others. In general, more promising results have accrued from concurrent treatment, despite greater toxicity, than from sequential use of drugs and radiation. CONCLUSION: Clinical gains from combined treatment with radiation and drugs have been small. New, mechanistically based approaches to combined treatment are required.