Evaluation of Early and Late Toxicities in Chemoradiation Trials

Abstract

Combined chemoradiotherapy is increasingly becoming a standard of care for the nonoperative management of a variety of solid malignancies. A string of randomized controlled phase III trials have shown statistically significant and clinically relevant improvements in outcome, ostensibly without any apparent increase in late toxicity. However, the reliability and the sensitivity of toxicity reporting in most trials are questionable. Audits and phase IV studies suggest that the chemoradiotherapy success comes at a price in terms of late toxicity. This review presents some of the challenges in recording, analyzing, and reporting toxicity data. Methods for summarizing toxicity are reviewed, and a new investigational metric, the TAME reporting system, is discussed. The need for special vigilance in the era of molecular-targeted agents is emphasized because of the possibility that unexpected serious adverse events with a low incidence may occur. Finally, we discuss how progress in molecular pathology and radiation biology may provide novel opportunities for stratifying patients according to risk of adverse effects, interventional targets for reducing or treating adverse effects, and surrogate markers of normal-tissue injury.