title: Comparison of Single-fraction and Multi-fraction Stereotactic Radiotherapy for Patients with 18F-fluorodeoxyglucose Positron Emission Tomography-staged Pulmonary Oligometastases.
abstract: OBJECTIVE
  To compare outcomes of single-fraction and multi-fraction stereotactic ablative body radiotherapy (SABR) for pulmonary metastases.
  
  
  METHODS
  A retrospective review from two academic institutions of patients with one to three pulmonary metastases staged with (18)F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) scans. For single-fraction SABR, 26 Gy was prescribed for peripheral targets and 18 Gy for central targets. In the multi-fraction cohort, 48 Gy/4 or 50 Gy/5 was prescribed for peripheral targets and 50 Gy/5 was prescribed for central targets. Three-dimensional conformal radiotherapy (3D-CRT), intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) plans were delivered using heterogeneity corrections. Conformity indices at an intermediate dose (R50%) and at a high dose (R100%) were used to assess a relationship with the planning target volume (PTV). Overall survival, local and distant progression and toxicity rates were analysed from the date of treatment completion.
  
  
  RESULTS
  Between February 2010 and June 2013, 65 patients with 85 pulmonary metastases were reviewed. The median follow-up was 2.1 years. Metastases most commonly originated from colorectal cancer (31%), followed by non-small cell lung cancer (25%). 3D-CRT was used in 52 targets, IMRT in 21 and VMAT in 12. 3D-CRT showed a lower median R50% (P=0.01), but a higher median R100% than IMRT/VMAT (P=0.04). The R50% index was inversely correlated to the PTV with all techniques (P=0.01). Overall survival at 1 and 2 years in all patients was 93% (95% confidence interval 87-100%) and 71% (95% confidence interval 58-86%), respectively. The 2 year freedom from local and distant progression was 93% (95% confidence interval 86-100%) and 38% (95% confidence interval 27-55%), respectively. There were no significant differences between overall survival (P=0 .14), time to distant progression (P=0.06) or toxicity rates (P=0.75) between single- and multi-fraction cohorts.
  
  
  CONCLUSIONS
  We report comparable local control, overall survival and toxicity rates between single-fraction and multi-fraction SABR treatments in patients with FDG-PET-staged pulmonary oligometastases. We propose a guideline for R50% conformity incorporating 3D-CRT/IMRT/VMAT techniques with heterogeneity corrected planning algorithms.
authors.affiliation: Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, Australia; Division of Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, East Melbourne, Australia. Electronic address: shankar.siva@petermac.org.
authors.forename: S
authors.initials: S
authors.lastname: Siva
authors.affiliation: Division of Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, East Melbourne, Australia.
authors.forename: K
authors.initials: K
authors.lastname: Kirby
authors.affiliation: Department of Radiation Oncology, Northern Sydney Cancer Centre, Sydney, Australia.
authors.forename: H
authors.initials: H
authors.lastname: Caine
authors.affiliation: Division of Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, East Melbourne, Australia.
authors.forename: D
authors.initials: D
authors.lastname: Pham
authors.affiliation: Division of Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, East Melbourne, Australia.
authors.forename: T
authors.initials: T
authors.lastname: Kron
authors.affiliation: Department of Biostatistics and Clinical Trials, Peter MacCallum Cancer Centre, East Melbourne, Australia.
authors.forename: L
authors.initials: L
authors.lastname: Te Marvelde
authors.affiliation: Department of Radiation Oncology, Northern Sydney Cancer Centre, Sydney, Australia.
authors.forename: D
authors.initials: D
authors.lastname: Whalley
authors.affiliation: Department of Radiation Oncology, Northern Sydney Cancer Centre, Sydney, Australia.
authors.forename: M J
authors.initials: MJ
authors.lastname: Stevens
authors.affiliation: Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, Australia; Division of Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, East Melbourne, Australia.
authors.forename: F
authors.initials: F
authors.lastname: Foroudi
authors.affiliation: Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, Australia; Division of Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, East Melbourne, Australia.
authors.forename: M
authors.initials: M
authors.lastname: MacManus
authors.affiliation: Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, Australia; Division of Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, East Melbourne, Australia.
authors.forename: D
authors.initials: D
authors.lastname: Ball
authors.affiliation: Department of Radiation Oncology, Northern Sydney Cancer Centre, Sydney, Australia.
authors.forename: T
authors.initials: T
authors.lastname: Eade
mesh_terms: D000368:Aged; D019583:Dose Fractionation, Radiation; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics*; D005500:Follow-Up Studies; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000401:mortality / Q000556:secondary / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D009369:Neoplasms / Q000000981:diagnostic imaging / Q000401:mortality / Q000473:pathology / Q000601:surgery*; D049268:Positron-Emission Tomography / Q000379:methods*; D011379:Prognosis; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D016634:Radiosurgery; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods; D012189:Retrospective Studies; D015996:Survival Rate; D014018:Tissue Distribution
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
keywords: Conformity index; lung; metastases; positron emission tomography; radiosurgery; stereotactic body radiotherapy