Prognostic value of pretreatment 18F-FDG PET-CT in radiotherapy for patients with hepatocellular carcinoma

PURPOSE The purpose of this study was to investigate the predictable value of pretreatment (18)F-fluorodeoxyglucose positron emission tomography-computed tomography ((18)F-FDG PET-CT) in radiotherapy (RT) for patients with hepatocellular carcinoma (HCC) or portal vein tumor thrombosis (PVTT). MATERIALS AND METHODS We conducted a retrospective analysis of 36 stage I-IV HCC patients treated with RT. (18)F-FDG PET-CT was performed before RT. Treatment target was determined HCC or PVTT lesions by treatment aim. They were irradiated at a median prescription dose of 50 Gy. The response was evaluated within 3 months after completion of RT using the Response Evaluation Criteria in Solid Tumors (RECIST). Response rate, overall survival (OS), and the pattern of failure (POF) were analyzed. RESULTS The response rate was 61.1%. The statistically significant prognostic factor affecting response in RT field was maximal standardized uptake value (maxSUV) only. The high SUV group (maxSUV ≥ 5.1) showed the better radiologic response than the low SUV group (maxSUV < 5.1). The median OS were 996.0 days in definitive group and 144.0 days in palliative group. Factors affecting OS were the %reduction of alpha-fetoprotein (AFP) level in the definitive group and Child-Pugh class in the palliative group. To predict the POF, maxSUV based on the cutoff value of 5.1 was the only significant factor in distant metastasis group. CONCLUSION The results of this study suggest that the maxSUV of (18)F-FDG PET-CT may be a prognostic factor for treatment outcome and the POF after RT. A %reduction of AFP level and Child-Pugh class could be used to predict OS in HCC.