title: High-dose, conventionally fractionated thoracic reirradiation for lung tumors.
abstract: BACKGROUND
  Loco-regional recurrences and second primary lung tumors are not uncommon after high-dose thoracic radiotherapy. The availability of improved radiotherapy techniques increases options for reirradiation. We describe a single-institutional experience with high-dose conventional thoracic reirradiation for both loco-regional recurrences and new primary tumors.
  
  
  METHODS
  Retrospective chart review of patients undergoing reirradiation between February 2004 and February 2013.
  
  
  RESULTS
  Of 24 patients identified, 54% had a loco-regional recurrence, and 46% a new primary tumor. The majority (63%) had stage III NSCLC at both initial and second treatment; median interval between treatments was 51 months (5-189), median follow-up after reirradiation was 19.3 months (95% CI: 2.8-35.9). Median overall survival (OS) after reirradiation was 13.5 months, with 1-year survival 51%. Median event-free survival (EFS) was 8.4 months. Median time between reirradiation and local progression (n=8) or distant progression (n=8) was 6.7 and 11.8 months, respectively. Three patients died with possible grade 5 bleeding. Other toxicities were uncommon. Planning target volume (PTV) at reirradiation was the most important prognostic factor; PTV <300 versus ≥300cc was significantly associated with median OS (17.4 vs 8.2 months, p=0.03) and EFS (14.1 vs 5.5 months, p=0.03). Magnitude of overlap between the initial and subsequent PTVs, and between dose distributions, did not influence survival.
  
  
  CONCLUSIONS
  Thoracic reirradiation with high dose conventional radiotherapy appears to deliver a meaningful survival benefit in low volume new primary or recurrent lung cancer. Further studies are needed to confirm these findings, and to establish reliable normal tissue tolerance doses for reirradiation.
authors.affiliation: Department of Radiation Oncology, VU University Medical Center, Amsterdam, The Netherlands. Electronic address: g.griffioen@vumc.nl.
authors.forename: Gwendolyn H M J
authors.initials: GH
authors.lastname: Griffioen
authors.affiliation: Department of Radiation Oncology, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Max
authors.initials: M
authors.lastname: Dahele
authors.affiliation: Department of Radiation Oncology, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Patricia F
authors.initials: PF
authors.lastname: de Haan
authors.affiliation: Department of Epidemiology and Biostatistics, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Peter M
authors.initials: PM
authors.lastname: van de Ven
authors.affiliation: Department of Radiation Oncology, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Ben J
authors.initials: BJ
authors.lastname: Slotman
authors.affiliation: Department of Radiation Oncology, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Suresh
authors.initials: S
authors.lastname: Senan
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002289:Carcinoma, Non-Small-Cell Lung / Q000401:mortality / Q000532:radiotherapy*; D019583:Dose Fractionation, Radiation; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000401:mortality / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000401:mortality / Q000532:radiotherapy*; D009367:Neoplasm Staging; D013902:Radiography, Thoracic; D011882:Radiotherapy, High-Energy; D012189:Retrospective Studies; D016019:Survival Analysis; D016896:Treatment Outcome
keywords: Conventionally fractionated; High dose; Image-guided radiotherapy; Intensity modulated radiotherapy; Lung cancer; Reirradiation