The Value Of Gross Tumor Volume In Predicting The Prognosis Of Primary Liver Carcinoma Patients Treated With Radiotherapy

Purpose:Gross tumor volume (GTV) should be an independent prognostic factor affecting patients'survival. However, the value of GTV in predicting the prognosis remains to be established.This study evaluated the prognostic significance of GTV and the greatest tumor diameter (GTD) in patients with Child-Pugh A primary liver carcinoma (PLC) who had been treated with radiotherapy.Methods:Having been treated with radiotherapy, 102 Child-Pugh A PLC patients were enrolled in the Cancer Hospital of Guangxi Medical University from January of 2000 to December of 2006. Survival was determined through the Kaplan-Meier method and differences were assessed using the Log-rank test. Multivariate analysis was performed using the Cox proportional hazard regression model. The Spearman correlation analysis was used to determine the correlation coefficient. The predictive accuracy of GTV in determining the death of patients within 2 postoperative years was determined using the receiver operator characteristic curve (ROC) and was compared with the GTD.Results:Univariate analysis showed that the UICC/AJCC T stage, portal vein tumor thrombi (PVTT), GTD and GTV significantly influences the survival time of patients with PLC. Multivariate analysis showed that the GTV was a major independent prognostic factor for the patients with Child-Pugh A PLC treated with radiotherapy. The GTV correlated with the total liver volume (r=0.632, P<0.01), and so did the GTD (r=0.432, P<0.01) . The areas under the ROC curves of GTV and GTD of PLC patients treated with radiotherapy died in 2 years were 0.810 and 0.710, respectively. The optimum cut-off value of GTV was 251.5 cm3 with a sensitivity of 83.64% and specificity of 72.34%.The optimum cut-off value of GTD was 7.75 cm with a sensitivity of 72.72% and specificity of 65.96%. There was a significant difference between the areas under the receiver operator characteristic curve of the GTV and that of the GTD in predicting the 2-year survival rate (P=0.016). The 2-year survival rates in the GTV≤251.5 cm3 group and in the GTV>251.5 cm3 group were 74.5% and 22.4%, respectively (P<0.01). The 2-year survival rates in the GTD≤7.75 cm group and in the GTD>7.75 cm group were 62.6% and 27.9%, respectively (P<0.01). The areas under ROC curves of GTV and GTD of PLC patients treated with radiotherapy died in 5 years were respectively 0.807 and 0.684. The optimum cut-off value of GTV was 166 cm3 with sensitivity of 79.75% and specificity of 80.00%. The optimum cut-off value of GTD was 7.5cm with sensitivity of 67.09% and specificity of 66.67%. There was no significant difference between the area under the receiver operator characteristic curve of the GTV and that of the GTD in predicting the 5-year survival rate. The 5-year survival rates in the GTV≤166cm3 group and in the GTV>166 cm3 group were 42.8% and 6.0%, respectively (p<0.01). The 5-year survival rates in the GTD≤7.5cm group and in the GTD>7.5cm group were 29.8% and 10.0%, respectively (p<0.01). Conclusion:The GTV is a major independent prognostic factor for the patients with Child-Pugh A PLC treated with radiotherapy. The ability of GTV to predict 2-year survival rates is better than that of the GTD.