title: Recurrences after intensity modulated radiotherapy for head and neck squamous cell carcinoma more likely to originate from regions with high baseline [18F]-FDG uptake.
abstract: OBJECTIVE
  To analyze the recurrence pattern in relation to target volumes and (18)F-fluorodeoxyglucose (FDG) uptake on positron emission tomography in head and neck squamous cell carcinoma (HNSCC) patients treated with definitive chemoradiation.
  
  
  METHODS
  520 patients received radiotherapy for HNSCC from 2005 to 2009. Among 100 patients achieving complete clinical response and a later recurrence, 39 patients with 48 loco-regional failures had a recurrence CT scan before any salvage therapy. The estimated point of origin of each recurrence was transferred to the planning CT by deformable image co-registration. The recurrence position was then related to the delineated target volumes and iso-SUV-contours relative to the maximum standard uptake value (SUV). We defined the recurrence density as the total number of recurrences in a sub-volume divided by the sum of that volume for all patients.
  
  
  RESULTS
  54% (95% CI 37-69%) of recurrences originated inside the FDG-positive volume and 96% (95% CI 86-99%) in the high dose region. Recurrence density was significantly higher in the central target volumes (P<0.0001) and increased with increasing FDG avidity (P=0.036).
  
  
  CONCLUSIONS
  The detailed pattern-of-failure data analysis suggests that most recurrences occur in the FDG PET positive areas or the solid tumor.
authors.affiliation: Department of Oncology, Rigshospitalet, University of Copenhagen, Denmark.
authors.forename: Anne K
authors.initials: AK
authors.lastname: Due
authors.affiliation: Department of Oncology, Rigshospitalet, University of Copenhagen, Denmark. Electronic address: ivan.storgaard.vogelius@rh.regionh.dk.
authors.forename: Ivan R
authors.initials: IR
authors.lastname: Vogelius
authors.affiliation: Department of Oncology, Rigshospitalet, University of Copenhagen, Denmark; Niels Bohr Institute, University of Copenhagen, Denmark.
authors.forename: Marianne C
authors.initials: MC
authors.lastname: Aznar
authors.affiliation: Department of Oncology, Rigshospitalet, University of Copenhagen, Denmark; Department of Human Oncology, University of Wisconsin, Madison, United States; Greenebaum Cancer Center, Department of Epidemiology & Public Health, University of Maryland, Baltimore, United States.
authors.forename: Søren M
authors.initials: SM
authors.lastname: Bentzen
authors.affiliation: Department of Oncology, Rigshospitalet, University of Copenhagen, Denmark; Department of Clinical Physiology, Nuclear Medicine & PET, Rigshospitalet, University of Copenhagen, Denmark.
authors.forename: Anne K
authors.initials: AK
authors.lastname: Berthelsen
authors.affiliation: Niels Bohr Institute, University of Copenhagen, Denmark; Department of Science, Systems and Models, Roskilde University, Denmark.
authors.forename: Stine S
authors.initials: SS
authors.lastname: Korreman
authors.affiliation: Department of Clinical Physiology, Nuclear Medicine & PET, Rigshospitalet, University of Copenhagen, Denmark.
authors.forename: Annika
authors.initials: A
authors.lastname: Loft
authors.affiliation: Department of Oncology, Rigshospitalet, University of Copenhagen, Denmark.
authors.forename: Claus A
authors.initials: CA
authors.lastname: Kristensen
authors.affiliation: Department of Oncology, Rigshospitalet, University of Copenhagen, Denmark.
authors.forename: Lena
authors.initials: L
authors.lastname: Specht
mesh_terms: D002294:Carcinoma, Squamous Cell / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000532:radiotherapy*; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics*; D006258:Head and Neck Neoplasms / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000532:radiotherapy*; D006801:Humans; D064847:Multimodal Imaging / Q000379:methods; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging / Q000378:metabolism; D049268:Positron-Emission Tomography / Q000379:methods; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics*; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods; D000077195:Squamous Cell Carcinoma of Head and Neck; D014057:Tomography, X-Ray Computed / Q000379:methods
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
keywords: FDG-PET; Head and neck cancer; Pattern of failure; Radiotherapy; Recurrence