Lijun Chen ¹ Qiaoyuan Wu ^1* Jia Fu ^1* Mengjie Jiang ¹ Jialin Qiu ^1* Jiaomei Tao ^1* Litong Lin ^1* Shenshen Chen ^1* Yi Wu ^1* Zhengqiang Yang ^2* Jianxu Li ^1* Shixiong Liang ^1*

• ¹ Department of Radiation Oncology, Guangxi Medical University Cancer Hospital, Nanning, China
• ² Department of Interventional Therapy, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China

Radiotherapy (RT) plays an important role in treatment of hepatocellular carcinoma (HCC).To screen patients who benefit most from RT,a nomogram for survival prediction of RT based on a large sample of HCC patients was created and validated. Methods 2,252 cases collected from Surveillance, Epidemiology, and End Results (SEER) database were seperated into a training or an internal validation cohort in a 7 to 3 ratio (n=1,565:650). An external validation cohort of cases from our institude was obtained (n=403). LASSO regression and COX analyses were adopted to develop a nomogram for survival prediction.The decision curve analysis (DCA) ,calibration curve and time-dependent receiver operating characteristic curves (TROC) demonstrated the reliability of the predictive model.For HCC patients received RT,the analyses revealed independent survival prediction factors were T stage(T2 vs T1,hazard ratio(HR)=1.452, [95%CI,1.195-1.765],p<0.001;T3 vs T1,HR=1.469, [95%CI,1.168-1.846],p<0.001;T4 vs T1,HR=1.291, [95%CI,0.951-1.754],p=0.101),N stage(HR=1.555, [95%CI,1.338-1.805],p<0.001),M stage(HR=3.007, [95%CI,2.645-3.418],p<0.001),max tumor size(>2 and ≤5 vs ≤2 cm,HR=1.273, [95%CI,0.992-1.633],p=0.057;>5 and ≤10 vs ≤2 cm,HR=1.625, [95%CI,1.246-2.118],p<0.001;>10 vs ≤2 cm,HR=1.784 , [95%CI,1.335-2.385],p<0.001),MVI(HR=1.454, [95%CI,1.028-2.057],p=0.034),AFP(HR=1.573, [95%CI,1.315-1.882],p<0.001) and chemotherapy(HR=0.511, [95%CI,0.454-0.576],p<0.001).A nomogram constructed with these prognostic factors demonstrated outstanding predictive accuracy.The area under the curve(AUC) in the training cohort for predicting OS at 6-, 12-, 18-, and 24-month were 0.824 (95% CI 0.803-0.846), 0.824 (95% CI 0.802-0.845), 0.816 (95% CI 0.792-0.840) and 0.820 (95%CI 0.794-0.846) .The AUCs were similar in the other two cohorts.The DCA and calibration curve demonstrated the reliability of the predictive model. For patients who have been treated with RT,a nomogram constructed with T stage,N stage, M stage, tumor size,MVI,AFP and chemotherapy has good survival prediction ability.