title: A systematic review on the role of FDG-PET/CT in tumour delineation and radiotherapy planning in patients with esophageal cancer.
abstract: OBJECTIVE
  FDG-PET/CT has proven to be useful in the staging process of esophageal tumours. This review analysed the role of FDG-PET/CT in tumour delineation and radiotherapy planning in comparison with CT alone among patients with esophageal cancer. Thereby we focused on the detection of the primary tumour and lymph nodes by FDG-PET/CT, changes in target volume (TV) delineation based on FDG-PET/CT and its validity, changes in inter- and intra-observer variability in TV delineation, consequences for radiotherapy treatment planning with regard to either target volumes or organs at risk and finally on the validation of FDG-PET/CT-based TVs in terms of treatment outcome.
  
  
  METHODS
  A literature search was performed in MEDLINE and Cochrane library databases for studies concerning the current value of FDG-PET/CT in tumour detection and delineation and radiotherapy-planning procedures among patients with esophageal cancer. Both prospective and retrospective studies were included.
  
  
  RESULTS
  Fifty publications met the eligibility criteria, of which 19 were review papers and one was a case report. The remaining 30 publications reported on the results of original studies. FDG-PET was able to identify most primary tumours, with a sensitivity and specificity for the detection of metastatic lymph nodes of 30-93% and 79-100%. The use of FDG-PET/CT resulted in changes of target volumes, and consequently in changes in treatment planning. However, evidence supporting the validity of the use of FDG-PET/CT in the tumour delineation process is very limited. Only three studies reported a significant positive correlation between FDG-PET-based tumour lengths and pathological findings. There were two studies that tested the influence of FDG-PET/CT to the inter- and intra-observer variability. One of them found a significant decrease in inter- and intra-observer variability, while the others did not. Furthermore, there are no studies demonstrating the use of PET/CT in terms of improved locoregional control or survival.
  
  
  CONCLUSIONS
  Since the literature is very limited standard implementation of FDG-PET/CT into the tumour delineation process for radiation treatment seems unjustified and needs further clinical validation first.
authors.affiliation: Department of Radiation Oncology, University of Groningen, Groningen, The Netherlands. c.t.muijs@rt.umcg.nl
authors.forename: Christina T
authors.initials: CT
authors.lastname: Muijs
authors.forename: Jannet C
authors.initials: JC
authors.lastname: Beukema
authors.forename: Jan
authors.initials: J
authors.lastname: Pruim
authors.forename: Veronique E
authors.initials: VE
authors.lastname: Mul
authors.forename: Henk
authors.initials: H
authors.lastname: Groen
authors.forename: John Th
authors.initials: JT
authors.lastname: Plukker
authors.forename: Johannes A
authors.initials: JA
authors.lastname: Langendijk
mesh_terms: D004938:Esophageal Neoplasms / Q000175:diagnosis* / Q000532:radiotherapy*; D019788:Fluorodeoxyglucose F18; D006801:Humans; D009367:Neoplasm Staging; D049268:Positron-Emission Tomography; D011880:Radiotherapy Planning, Computer-Assisted; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
chemical_list: D019788:Fluorodeoxyglucose F18