title: The PET-boost randomised phase II dose-escalation trial in non-small cell lung cancer.
abstract: OBJECTIVE
  The local site of relapse in non-small cell lung cancer (NSCLC) is primarily located in the high FDG uptake region of the primary tumour prior to treatment. A phase II PET-boost trial (NCT01024829) randomises patients between dose-escalation of the entire primary tumour (arm A) or to the high FDG uptake region inside the primary tumour (>50% SUV(max)) (arm B), whilst giving 66 Gy in 24 fractions to involved lymph nodes. We analysed the planning results of the first 20 patients for which both arms A and B were planned.
  
  
  METHODS
  Boost dose levels were escalated up to predefined normal tissue constraints with an equal mean lung dose in both arms. This also forces an equal mean PTV dose in both arms, hence testing pure dose-redistribution. Actual delivered treatment plans from the ongoing clinical trial were analysed. Patients were randomised between arms A and B if dose-escalation to the primary tumour in arm A of at least 72 Gy in 24 fractions could be safely planned.
  
  
  RESULTS
  15/20 patients could be escalated to at least 72 Gy. Average prescribed fraction dose was 3.27±0.31 Gy [3.01-4.28 Gy] and 3.63±0.54 Gy [3.20-5.40 Gy] for arms A and B, respectively. Average mean total dose inside the PTV of the primary tumour was comparable: 77.3±7.9 Gy vs. 77.5±10.1 Gy. For the boost region dose levels of on average 86.9±14.9 Gy were reached. No significant dose differences between both arms were observed for the organs at risk. Most frequent observed dose-limiting constraints were the mediastinal structures (13/15 and 14/15 for arms A and B, respectively), and the brachial plexus (3/15 for both arms).
  
  
  CONCLUSIONS
  Dose-escalation using an integrated boost could be achieved to the primary tumour or high FDG uptake regions whilst keeping the pre-defined dose constraints.
authors.affiliation: Department of Radiation Oncology, Maastricht University Medical Centre, Maastricht, The Netherlands. wouter.vanelmpt@maastro.nl
authors.forename: Wouter
authors.initials: W
authors.lastname: van Elmpt
authors.forename: Dirk
authors.initials: D
authors.lastname: De Ruysscher
authors.forename: Anke
authors.initials: A
authors.lastname: van der Salm
authors.forename: Annemarie
authors.initials: A
authors.lastname: Lakeman
authors.forename: Judith
authors.initials: J
authors.lastname: van der Stoep
authors.forename: Daisy
authors.initials: D
authors.lastname: Emans
authors.forename: Eugène
authors.initials: E
authors.lastname: Damen
authors.forename: Michel
authors.initials: M
authors.lastname: Öllers
authors.forename: Jan-Jakob
authors.initials: JJ
authors.lastname: Sonke
authors.forename: José
authors.initials: J
authors.lastname: Belderbos
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002289:Carcinoma, Non-Small-Cell Lung / Q000532:radiotherapy*; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D047368:Tumor Burden