title: Usefulness of positron emission tomography with fluorine-18-fluorodeoxyglucose in predicting treatment response in unresectable hepatocellular carcinoma patients treated with external beam radiotherapy.
abstract: OBJECTIVE
  To assess the significance of the ratio between standardized uptake values (SUV) of tumor and normal liver tissue obtained from positron emission tomography with fluorine-18-fluorodeoxyglucose (FDG-PET) in predicting the response of hepatocellular carcinoma (HCC) patients treated with external beam radiotherapy (EBRT).
  
  
  METHODS
  We retrospectively analyzed 35 HCC patients who were treated with EBRT between January 2004 and June 2007. All patients underwent FDG-PET in which SUV values were obtained from tumor and normal liver tissues and were used to calculate the ratios (SUV(Tumor)/SUV(Liver)). After FDG-PET, patients received liver treatment including concurrent chemoradiation, transarterial chemoembolization plus RT, or intraarterial chemotherapy plus RT. Using three-dimensional conformal RT, median dose of 45 Gy was delivered in conventional fractions. Patients underwent abdominal/pelvic CT 1 month after RT, and treatment responses were evaluated according to the Response Evaluation Criteria in Solid Tumors criteria.
  
  
  RESULTS
  Patients were divided into high-SUV ratio group (n = 20) and low-SUV ratio group (n = 15) according to SUV ratio at a cutoff value of 2.5. Objective responses consisting of either complete response (CR) or partial response (PR) were observed in 16 and 6 patients (46% vs. 17%, p = 0.015), respectively; median survivals after RT were 8 months and 5 months (p = 0.41) for the high-SUV ratio group and the low-SUV ratio group, respectively. Rates of intrahepatic metastases (9% vs. 11%, p = 0.39) and distant metastases (32% vs. 32%, p = 0.27) showed no significant difference between two groups.
  
  
  CONCLUSIONS
  External beam RT for HCC patients with higher SUV ratios resulted in higher response rates than for patients with lower SUV ratios. Treatment of HCC with higher SUV ratios did not result in increased survival; high rates of intrahepatic and distant metastases in both SUV groups may have affected patient survival. SUV ratios from pre-RT FDG-PET may be beneficial for selecting patients who are likely to respond to EBRT for unresectable HCC.
authors.affiliation: Department of Radiation Oncology, Yonsei Cancer Center, Yonsei University College of Medicine, Yonsei University Health System, Seoul, Korea.
authors.forename: Jun Won
authors.initials: JW
authors.lastname: Kim
authors.forename: Jinsil
authors.initials: J
authors.lastname: Seong
authors.forename: Mijin
authors.initials: M
authors.lastname: Yun
authors.forename: Ik Jae
authors.initials: IJ
authors.lastname: Lee
authors.forename: Hong In
authors.initials: HI
authors.lastname: Yoon
authors.forename: Ho Jin
authors.initials: HJ
authors.lastname: Cho
authors.forename: Kwang-Hyub
authors.initials: KH
authors.lastname: Han
mesh_terms: D000328:Adult; D000368:Aged; D006528:Carcinoma, Hepatocellular / Q000000981:diagnostic imaging / Q000378:metabolism / Q000556:secondary / Q000628:therapy; D016461:Chemoembolization, Therapeutic / Q000379:methods; D059248:Chemoradiotherapy / Q000379:methods; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics; D005472:Fluorouracil / Q000008:administration & dosage; D005947:Glucose / Q000378:metabolism; D006801:Humans; D008099:Liver / Q000000981:diagnostic imaging* / Q000378:metabolism; D008113:Liver Neoplasms / Q000000981:diagnostic imaging / Q000378:metabolism / Q000628:therapy; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D012074:Remission Induction; D012189:Retrospective Studies; D016896:Treatment Outcome
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D005947:Glucose; D005472:Fluorouracil