title: Prognostic value of gross tumor volume delineated by FDG-PET-CT based radiotherapy treatment planning in patients with locally advanced pancreatic cancer treated with chemoradiotherapy.
abstract: BACKGROUND
  We aimed to assess whether gross tumor volume (GTV) determined by fusion of contrast-enhanced computerized tomography (CT) and 18F-fluoro-deoxy-D-glucose positron emission tomography-CT (FDG-PET-CT) based radiotherapy planning could predict outcomes, namely overall survival (OS), local-regional progression-free survival (LRPFS), and progression-free survival (PFS) in cases with locally advanced pancreas cancer (LAPC) treated with definitive concurrent chemoradiotherapy.
  
  
  METHODS
  A total of 30 patients with histological proof of LAPC underwent 50.4 Gy (1.8 Gy/28 fractions) of radiotherapy concurrent with continuously infused 5-FU followed by 4 to 6 courses of maintenance gemcitabine. Target volume delineations were performed on FDG-PET-CT-based RTP. Patients were stratified into 2 groups: GTV lesser (GTVL) versus greater (GTVG) than cut off value determined by receiver operating characteristic (ROC) analysis, and compared in terms of OS, LRPFS and PFS.
  
  
  RESULTS
  Median GTV delineated according to the FDG-PET-CT data was 100.0 cm3. Cut off GTV value determined from ROC curves was 91.1 cm3. At a median follow up of 11.2 months, median OS, LRPFS and PFS for the entire population were 10.3, 7.8 and 5.7 months, respectively. Median OS, LRPFS and PFS for GTVL and GTVG cohorts were 16.3 vs. 9.5 (p = 0.005), 11.0 vs. 6.0 (p = 0.013), and 9.0 vs. 4.8 months (p = 0.008), respectively.
  
  
  CONCLUSIONS
  The superior OS, LRPFS and PFS observed in GTVL patients over GTVG ones suggests a potential for FDG-PET-CT-defined GTV size in predicting outcomes of LAPC patients treated with definitive C-CRT, which needs to be validated by further studies with larger cohorts.
authors.affiliation: Baskent University Adana Medical Faculty, Department of Radiation Oncology, Kisla Saglik Yerleskesi, Adana, Turkey. cemparlak@gmail.com
authors.forename: Cem
authors.initials: C
authors.lastname: Parlak
authors.forename: Erkan
authors.initials: E
authors.lastname: Topkan
authors.forename: Cem
authors.initials: C
authors.lastname: Onal
authors.forename: Mehmet
authors.initials: M
authors.lastname: Reyhan
authors.forename: Ugur
authors.initials: U
authors.lastname: Selek
mesh_terms: D000328:Adult; D000368:Aged; D019540:Area Under Curve; D059248:Chemoradiotherapy; D018572:Disease-Free Survival; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging / Q000379:methods*; D009367:Neoplasm Staging; D010190:Pancreatic Neoplasms / Q000401:mortality* / Q000473:pathology* / Q000628:therapy; D049268:Positron-Emission Tomography; D011379:Prognosis; D012372:ROC Curve; D019275:Radiopharmaceuticals; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D014057:Tomography, X-Ray Computed; D047368:Tumor Burden / Q000187:drug effects / Q000528:radiation effects
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18