title: Results of a multicentric in silico clinical trial (ROCOCO): comparing radiotherapy with photons and protons for non-small cell lung cancer.
abstract: BACKGROUND
  This multicentric in silico trial compares photon and proton radiotherapy for non-small cell lung cancer patients. The hypothesis is that proton radiotherapy decreases the dose and the volume of irradiated normal tissues even when escalating to the maximum tolerable dose of one or more of the organs at risk (OAR).
  
  
  METHODS
  Twenty-five patients, stage IA-IIIB, were prospectively included. On 4D F18-labeled fluorodeoxyglucose-positron emission tomography-computed tomography scans, the gross tumor, clinical and planning target volumes, and OAR were delineated. Three-dimensional conformal radiotherapy (3DCRT) and intensity-modulated radiotherapy (IMRT) photon and passive scattered conformal proton therapy (PSPT) plans were created to give 70 Gy to the tumor in 35 fractions. Dose (de-)escalation was performed by rescaling to the maximum tolerable dose.
  
  
  RESULTS
  Protons resulted in the lowest dose to the OAR, while keeping the dose to the target at 70 Gy. The integral dose (ID) was higher for 3DCRT (59%) and IMRT (43%) than for PSPT. The mean lung dose reduced from 18.9 Gy for 3DCRT and 16.4 Gy for IMRT to 13.5 Gy for PSPT. For 10 patients, escalation to 87 Gy was possible for all 3 modalities. The mean lung dose and ID were 40 and 65% higher for photons than for protons, respectively.
  
  
  CONCLUSIONS
  The treatment planning results of the Radiation Oncology Collaborative Comparison trial show a reduction of ID and the dose to the OAR when treating with protons instead of photons, even with dose escalation. This shows that PSPT is able to give a high tumor dose, while keeping the OAR dose lower than with the photon modalities.
authors.affiliation: Department of Radiation Oncology (MAASTRO), GROW-School for Oncology and Developmental Biology, Maastricht University Medical Center (MUMC+), Maastricht, The Netherlands. Erik.Roelofs@maastro.nl
authors.forename: Erik
authors.initials: E
authors.lastname: Roelofs
authors.forename: Martijn
authors.initials: M
authors.lastname: Engelsman
authors.forename: Coen
authors.initials: C
authors.lastname: Rasch
authors.forename: Lucas
authors.initials: L
authors.lastname: Persoon
authors.forename: Sima
authors.initials: S
authors.lastname: Qamhiyeh
authors.forename: Dirk
authors.initials: D
authors.lastname: de Ruysscher
authors.forename: Frank
authors.initials: F
authors.lastname: Verhaegen
authors.forename: Madelon
authors.initials: M
authors.lastname: Pijls-Johannesma
authors.forename: Philippe
authors.initials: P
authors.lastname: Lambin
mesh_terms: D002289:Carcinoma, Non-Small-Cell Lung / Q000473:pathology / Q000532:radiotherapy*; D003198:Computer Simulation; D019583:Dose Fractionation, Radiation; D006801:Humans; D008175:Lung Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D020714:Maximum Tolerated Dose; D058958:Organs at Risk / Q000528:radiation effects; D017785:Photons / Q000627:therapeutic use*; D061766:Proton Therapy; D011829:Radiation Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D020266:Radiotherapy, Conformal; D050397:Radiotherapy, Intensity-Modulated; D011522:Protons
chemical_list: D011522:Protons