title: FDG-PET/CT during concomitant chemo radiotherapy for esophageal cancer: Reducing target volumes to deliver higher radiotherapy doses.
abstract: BACKGROUND
  A planning study investigated whether reduced target volumes defined on FDG-PET/CT during radiotherapy allow total dose escalation without compromising normal tissue tolerance in patients with esophageal cancer.
  
  
  METHODS
  Ten patients with esophageal squamous cell carcinoma (SCC), candidate to curative-intent concomitant chemo-radiotherapy (CRT), had FDG-PET/CT performed in treatment position, before and during (Day 21) radiotherapy (RT). Four planning scenarios were investigated: 1) 50 Gy total dose with target volumes defined on pre-RT FDG-PET/CT; 2) 50 Gy with boost target volume defined on FDG-PET/CT during RT; 3) 66 Gy with target volumes from pre-RT FDG-PET/CT; and 4) 66 Gy with boost target volume from during-RT FDG-PET/CT.
  
  
  RESULTS
  The median metabolic target volume decreased from 12.9 cm3 (minimum 3.7-maximum 44.8) to 5.0 cm3 (1.7-13.5) (p=0.01) between pre- and during-RCT FDG-PET/CT. The median PTV66 was smaller on during-RT than on baseline FDG-PET/CT [108 cm3 (62.5-194) vs. 156 cm3 (68.8-251), p=0.02]. When total dose was set to 50 Gy, planning on during-RT FDG-PET/CT was associated with a marginal reduction in normal tissues irradiation. When total dose was increased to 66 Gy, planning on during-RT PET yielded significantly lower doses to the spinal cord [Dmax=44.1Gy (40.8-44.9) vs. 44.7Gy (41.5-45.0), p=0.007] and reduced lung exposure [V20Gy=23.2% (17.3-27) vs. 26.8% (19.7-30.2), p=0.006].
  
  
  CONCLUSIONS
  This planning study suggests that adaptive RT based on target volume reduction assessed on FDG-PET/CT during treatment could facilitate dose escalation up to 66 Gy in patients with esophageal SCC.
authors.affiliation: Radiation Oncology and Medical Physics, QuantIF-LITIS (EA4108), Henri Becquerel Center and Rouen University Hospital, University of Rouen , France.
authors.forename: Lamyaa
authors.initials: L
authors.lastname: Nkhali
authors.forename: Sébastien
authors.initials: S
authors.lastname: Thureau
authors.forename: Agathe
authors.initials: A
authors.lastname: Edet-Sanson
authors.forename: Kaya
authors.initials: K
authors.lastname: Doyeux
authors.forename: Ahmed
authors.initials: A
authors.lastname: Benyoucef
authors.forename: Isabelle
authors.initials: I
authors.lastname: Gardin
authors.forename: Pierre
authors.initials: P
authors.lastname: Michel
authors.forename: Pierre
authors.initials: P
authors.lastname: Vera
authors.forename: Bernard
authors.initials: B
authors.lastname: Dubray
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002294:Carcinoma, Squamous Cell / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000532:radiotherapy*; D059248:Chemoradiotherapy; D004938:Esophageal Neoplasms / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000532:radiotherapy*; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008168:Lung; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D058958:Organs at Risk; D049268:Positron-Emission Tomography; D011446:Prospective Studies; D011829:Radiation Dosage; D019275:Radiopharmaceuticals; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D013116:Spinal Cord; D013997:Time Factors; D014057:Tomography, X-Ray Computed
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18