Purpose: The purpose of this study was to identify radiotherapeutic parameters for predicting the occurrence of liver complications induced by radiotherapy of a liver tumor.
Methods and materials: From 2001 to 2003, a total of 131 patients with hepatocellular carcinoma received three-dimensional conformal radiotherapy. The total dose was determined by the fraction of nontumor liver receiving 50% of the isocenter dose (V(50%)). We evaluated three sets of published radiation dose guidelines using nontumor liver volume or a combination of nontumor liver volume and hepatic functional reserve. The V(50%) was divided into three intervals (<33%, 33-66%, and >66%) and four categories (<25%, 25-49%, 50-75%, and >75%) according to guidelines by the University of Michigan and the Yonsei University, respectively. According to the guideline of Cheng et al., the radiation dose was determined by the indocyanin green retention rate at 15 min (ICG-R15) and the nontumor liver volume.
Results: Of the 131 patients, 13 patients (9.9%) presented with liver complications. The incidence was 11.1%, 10.3%, and 18.2%, respectively, for a V(50%) of less than 33%, 33% to 66%, and more than 66%. The observed hepatic toxicity incidence was 10%, 12.1%, and 10.4% respectively for a V(50%) of less than 25%, 25% to 49%, and 50% to 75%, respectively. Nontumor liver volume and ICG-R15 were not predictors of liver complications. The incidence of liver complications was significantly increased in patients with Child-Pugh Class B (p = 0.044).
Conclusions: The parameter, V(50%), can be divided into 4 categories and used to predict acceptable toxicity. Furthermore, indicators of liver functional status like the Child-Pugh class may be more important and useful parameters than ICG-R15 for predicting radiation-related liver disease.