title: Radiotherapy for GIST progressing during or after tyrosine kinase inhibitor therapy: A prospective study.
abstract: OBJECTIVE
  Gastrointestinal stromal tumor (GIST) has been considered radiation-resistant, and radiotherapy is recommended only for palliation of bone metastases in current treatment guidelines. No registered prospective trial has evaluated GIST responsiveness to radiotherapy.
  
  
  METHODS
  Patients with GIST progressing at intra-abdominal sites or the liver were entered to this prospective Phase II multicenter study (identifier NCT00515931). Metastases were treated with external beam radiotherapy using either conformal 3D planning or intensity modulated radiotherapy and conventional fractionation to a cumulative planning target volume dose of approximately 40 Gy. Systemic therapy was maintained unaltered during the study.
  
  
  RESULTS
  Of the 25 patients entered, 19 were on concomitant tyrosine kinase inhibitor therapy, most often imatinib. Two (8%) patients achieved partial remission, 20 (80%) had stable target lesion size for ⩾3 months after radiotherapy with a median duration of stabilization of 16 months, and 3 (12%) progressed. The median time to radiotherapy target lesion progression was 4-fold longer than the median time to GIST progression at any site (16 versus 4 months). Radiotherapy was generally well tolerated.
  
  
  CONCLUSIONS
  Responses to radiotherapy were infrequent, but most patients had durable stabilization of the target lesions. GIST patients with soft tissue metastases benefit frequently from radiotherapy.
authors.affiliation: Department of Oncology, Helsinki University Hospital and University of Helsinki, Finland. Electronic address: heikki.joensuu@hus.fi.
authors.forename: Heikki
authors.initials: H
authors.lastname: Joensuu
authors.affiliation: Department of Oncology, Lund University, Sweden.
authors.forename: Mikael
authors.initials: M
authors.lastname: Eriksson
authors.affiliation: Department of Oncology, Helsinki University Hospital and University of Helsinki, Finland.
authors.forename: Juhani
authors.initials: J
authors.lastname: Collan
authors.affiliation: Department of Radiology, HUS Medical Imaging Center, Helsinki University Hospital and University of Helsinki, Finland.
authors.forename: Marja H
authors.initials: MH
authors.lastname: Balk
authors.affiliation: Department of Oncology, University Hospital Lausanne, Switzerland.
authors.forename: Serge
authors.initials: S
authors.lastname: Leyvraz
authors.affiliation: Department of Oncology, University Hospital Lausanne, Switzerland.
authors.forename: Michael
authors.initials: M
authors.lastname: Montemurro
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D059248:Chemoradiotherapy; D005260:Female; D005770:Gastrointestinal Neoplasms / Q000188:drug therapy / Q000532:radiotherapy*; D046152:Gastrointestinal Stromal Tumors / Q000188:drug therapy / Q000532:radiotherapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D047428:Protein Kinase Inhibitors / Q000627:therapeutic use*; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors*; D011880:Radiotherapy Planning, Computer-Assisted
chemical_list: D047428:Protein Kinase Inhibitors; D011505:Protein-Tyrosine Kinases
keywords: Gastrointestinal stromal tumor (GIST); Imatinib; Radiotherapy; Sunitinib