title: Distribution of lymph node metastases on FDG-PET/CT in inoperable or unresectable oesophageal cancer patients and the impact on target volume definition in radiation therapy.
abstract: BACKGROUND
  Definitive chemoradiotherapy (dCRT) is standard care for localised inoperable/unresectable oesophageal tumours. Many surgical series have reported on distribution of lymph node metastases (LNM) in resected patients. However, no data is available on the distribution of at-risk LN regions in this more unfavourable patient group. This study aimed to determine the spread of LNM using FDG-PET/CT, to compare it with the distribution in surgical series and to define its impact on the definition of elective LN irradiation (ENI).
  
  
  METHODS
  FDG-PET/CT images of patients with oesophageal cancer treated with dCRT (from 2003 to 2013) were reviewed to identify the anatomic distribution of FDG-avid LNs. Tumours were divided according to proximal, mid-thoracic or distal localisation.
  
  
  RESULTS
  About 105 consecutive patients entered analysis. The highest numbers of FDG-avid LNs in proximal tumours were at LN station 101R (45%) and 106recL (35%). For mid-thoracic tumours at 104R (30%) and 105 (30%). For tumours located in the distal oesophagus, the most common sites were along the lesser curvature of the stomach (21%) and the left gastric artery (21%). Except for the supraclavicular and pretracheal nodes, there were no positive locoregional LNM found outside the standard surgical resection area.
  
  
  CONCLUSIONS
  Our results show a good correlation between the distribution of nodal volumes at risk in surgical series and on FDG-PET/CT. The results can be used to determine target definition in dCRT for oesophageal cancer. For mid-thoracic tumours, the current target delineation guidelines may be extended based on the risk of node involvement, but more clinical studies are needed to determine if the potential harm of expanding the CTV outweighs the potential benefit.
authors.affiliation: Department of Radiation Oncology, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Melanie
authors.initials: M
authors.lastname: Machiels
authors.affiliation: Department of Radiation Oncology, Isala Clinics Zwolle, Zwolle, The Netherlands.
authors.forename: Sanne J
authors.initials: SJ
authors.lastname: Wouterse
authors.affiliation: Department of Radiation Oncology, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Elisabeth D
authors.initials: ED
authors.lastname: Geijsen
authors.affiliation: Department of Radiation Oncology, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Rob M
authors.initials: RM
authors.lastname: van Os
authors.affiliation: Department of Nuclear Medicine, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Roel J
authors.initials: RJ
authors.lastname: Bennink
authors.affiliation: Department of Medical Oncology, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Hanneke Wm
authors.initials: HW
authors.lastname: van Laarhoven
authors.affiliation: Department of Radiation Oncology, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Maarten Ccm
authors.initials: MC
authors.lastname: Hulshof
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004938:Esophageal Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000532:radiotherapy*; D004947:Esophagus / Q000000981:diagnostic imaging / Q000473:pathology; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008207:Lymphatic Metastasis / Q000000981:diagnostic imaging / Q000532:radiotherapy; D008297:Male; D008875:Middle Aged; D000072078:Positron Emission Tomography Computed Tomography / Q000379:methods*; D019275:Radiopharmaceuticals; D012189:Retrospective Studies
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
keywords: FDG-PET/CT; definitive chemoradiotherapy; elective lymph node irradiation; lymph node metastases; oesophageal cancer; target volume definition