[Classification of early and late radiation reactions and injuries]

Radiation tolerance of normal tissues remains the limiting factor for delivering crucial tumoridical dose. The late toxicity of normal tissues is the most element of an irradiation: somatic, functional and structural alterations occur during the actual treatment itself, but late effects manifest months to years after acute effects heal, and may progress with time. The optimal therapeutic ratio ultimately requires not only complete tumor clearance, but also minimal residual injury to surrounding vital normal tissues. The disparity between the intensity of acute and late effects and the inability to predict the eventual manifestations of late normal tissue injury has made radiation oncologists recognize the importance of careful patient follow-up. There is so far no uniform toxicity scoring system to compare several clinical studies in the absence of a "common toxicity language". This justifies the need to establish a precise evaluation system for the analysis of late effects of radiation on normal tissues. The current proposed scales are not yet validated, and should be used cautiously. The present toxicity scale for acute and late radiation complications is not complete. It bases on analyses and additions of existent system as CTC (Common Toxicity Criteria) and SOMALENT by EORTC/RTOG. Current classification can be used for quantitative definition of complications' grade and for treatment planning.