title: Does selective pleural irradiation of malignant pleural mesothelioma allow radiation dose escalation? : A planning study.
abstract: BACKGROUND
  After lung-sparing radiotherapy for malignant pleural mesothelioma (MPM), local failure at sites of previous gross disease represents the dominant form of failure. Our aim is to investigate if selective irradiation of the gross pleural disease only can allow dose escalation.
  
  
  METHODS
  In all, 12 consecutive stage I-IV MPM patients (6 left-sided and 6 right-sided) were retrospectively identified and included. A magnetic resonance imaging-based pleural gross tumor volume (GTV) was contoured. Two sets of planning target volumes (PTV) were generated for each patient: (1) a "selective" PTV (S-PTV), originating from a 5-mm isotropic expansion from the GTV and (2) an "elective" PTV (E-PTV), originating from a 5-mm isotropic expansion from the whole ipsilateral pleural space. Two sets of volumetric modulated arc therapy (VMAT) treatment plans were generated: a "selective" pleural irradiation plan (SPI plan) and an "elective" pleural irradiation plan (EPI plan, planned with a simultaneous integrated boost technique [SIB]).
  
  
  RESULTS
  In the SPI plans, the average median dose to the S‑PTV was 53.6 Gy (range 41-63.6 Gy). In 4 of 12 patients, it was possible to escalate the dose to the S‑PTV to >58 Gy. In the EPI plans, the average median doses to the E‑PTV and to the S‑PTV were 48.6 Gy (range 38.5-58.7) and 49 Gy (range 38.6-59.5 Gy), respectively. No significant dose escalation was achievable.
  
  
  CONCLUSIONS
  The omission of the elective irradiation of the whole ipsilateral pleural space allowed dose escalation from 49 Gy to more than 58 Gy in 4 of 12 chemonaive MPM patients. This strategy may form the basis for nonsurgical radical combined modality treatment of MPM.
authors.affiliation: Department of Oncology, Experimental Radiation Oncology, KU Leuven - University of Leuven, 3000, Leuven, Belgium. angela.botticella@kuleuven.be.
authors.forename: A
authors.initials: A
authors.lastname: Botticella
authors.affiliation: Department of Oncology, Experimental Radiation Oncology, KU Leuven - University of Leuven, 3000, Leuven, Belgium.
authors.forename: G
authors.initials: G
authors.lastname: Defraene
authors.affiliation: Department of Respiratory Medicine, KU Leuven - University of Leuven, University Hospitals Leuven, 3000, Leuven, Belgium.
authors.forename: K
authors.initials: K
authors.lastname: Nackaerts
authors.affiliation: Nuclear Medicine, KU Leuven - University of Leuven, University Hospitals Leuven, 3000, Leuven, Belgium.
authors.forename: C
authors.initials: C
authors.lastname: Deroose
authors.affiliation: Radiology Department, KU Leuven - University of Leuven, University Hospitals Leuven, 3000, Leuven, Belgium.
authors.forename: J
authors.initials: J
authors.lastname: Coolen
authors.affiliation: Department of Thoracic Surgery, University Hospitals Leuven, 3000, Leuven, Belgium.
authors.forename: P
authors.initials: P
authors.lastname: Nafteux
authors.affiliation: Department of Radiation Oncology, University Hospitals Leuven, 3000, Leuven, Belgium.
authors.forename: B
authors.initials: B
authors.lastname: Vanstraelen
authors.affiliation: Institute Paramedical Studies, Medical Imaging and Radiotherapeutic Techniques, Fontys University of Applied Science, Eindhoven, The Netherlands.
authors.forename: S
authors.initials: S
authors.lastname: Joosten
authors.affiliation: Institute Paramedical Studies, Medical Imaging and Radiotherapeutic Techniques, Fontys University of Applied Science, Eindhoven, The Netherlands.
authors.forename: L A W
authors.initials: LAW
authors.lastname: Michiels
authors.affiliation: Department of Oncology, Experimental Radiation Oncology, KU Leuven - University of Leuven, 3000, Leuven, Belgium.|Department of Radiation Oncology, University Hospitals Leuven, 3000, Leuven, Belgium.
authors.forename: S
authors.initials: S
authors.lastname: Peeters
authors.affiliation: Department of Oncology, Experimental Radiation Oncology, KU Leuven - University of Leuven, 3000, Leuven, Belgium.|GROW - School for Oncology and Developmental Biology, Department of Radiation Oncology (MAASTRO Clinic), Maastricht University Medical Center, Maastricht, The Netherlands.
authors.forename: D
authors.initials: D
authors.lastname: De Ruysscher
mesh_terms: D019583:Dose Fractionation, Radiation; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D008297:Male; D008654:Mesothelioma / Q000532:radiotherapy*; D008875:Middle Aged; D010994:Pleura / Q000528:radiation effects*; D010997:Pleural Neoplasms / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*
keywords: Elective pleural irradiation; Lung-sparing VMAT; Malignant pleural mesothelioma; Nonsurgical treatments; Selective pleural irradiation