title: An individual patient data metaanalysis of outcomes and prognostic factors after treatment of oligometastatic non-small-cell lung cancer.
abstract: BACKGROUND
  An individual patient data metaanalysis was performed to determine clinical outcomes, and to propose a risk stratification system, related to the comprehensive treatment of patients with oligometastatic NSCLC.
  
  
  METHODS
  After a systematic review of the literature, data were obtained on 757 NSCLC patients with 1 to 5 synchronous or metachronous metastases treated with surgical metastectomy, stereotactic radiotherapy/radiosurgery, or radical external-beam radiotherapy, and curative treatment of the primary lung cancer, from hospitals worldwide. Factors predictive of overall survival (OS) and progression-free survival were evaluated using Cox regression. Risk groups were defined using recursive partitioning analysis (RPA). Analyses were conducted on training and validating sets (two-thirds and one-third of patients, respectively).
  
  
  RESULTS
  Median OS was 26 months, 1-year OS 70.2%, and 5-year OS 29.4%. Surgery was the most commonly used treatment for the primary tumor (635 patients [83.9%]) and metastases (339 patients [62.3%]). Factors predictive of OS were: synchronous versus metachronous metastases (P < .001), N-stage (P = .002), and adenocarcinoma histology (P = .036); the model remained predictive in the validation set (c-statistic = 0.682). In RPA, 3 risk groups were identified: low-risk, metachronous metastases (5-year OS, 47.8%); intermediate risk, synchronous metastases and N0 disease (5-year OS, 36.2%); and high risk, synchronous metastases and N1/N2 disease (5-year OS, 13.8%).
  
  
  CONCLUSIONS
  Significant OS differences were observed in oligometastatic patients stratified according to type of metastatic presentation, and N status. Long-term survival is common in selected patients with metachronous oligometastases. We propose this risk classification scheme be used in guiding selection of patients for clinical trials of ablative treatment.
authors.affiliation: Department of Radiation Oncology, London Health Sciences Centre, London, Ontario, Canada.
authors.forename: Allison B
authors.initials: AB
authors.lastname: Ashworth
authors.affiliation: Department of Radiation Oncology, VU University Medical Center, Amsterdam, Netherlands.
authors.forename: Suresh
authors.initials: S
authors.lastname: Senan
authors.affiliation: Department of Radiation Oncology, London Health Sciences Centre, London, Ontario, Canada.
authors.forename: David A
authors.initials: DA
authors.lastname: Palma
authors.affiliation: Department of Thoracic Surgery, Georges Pompidou European Hospital, Paris, France.
authors.forename: Marc
authors.initials: M
authors.lastname: Riquet
authors.affiliation: Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Yong Chan
authors.initials: YC
authors.lastname: Ahn
authors.affiliation: Department of Oncology, University of Turin, Turin, Italy.
authors.forename: Umberto
authors.initials: U
authors.lastname: Ricardi
authors.affiliation: Department of General Thoracic Surgery, Catholic University of Sacred Heart, Rome, Italy.
authors.forename: Maria T
authors.initials: MT
authors.lastname: Congedo
authors.affiliation: Division of Radiation Oncology, M.D. Anderson Cancer Center, Houston, TX.
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Gomez
authors.affiliation: University of Melbourne Department of Surgery, St Vincent's Hospital, Melbourne, Australia.
authors.forename: Gavin M
authors.initials: GM
authors.lastname: Wright
authors.affiliation: Department of Thoracic Surgery, San Raffaele Scientific Institute, Milan, Italy.
authors.forename: Giulio
authors.initials: G
authors.lastname: Melloni
authors.affiliation: Department of Radiation Oncology, University of Rochester, Rochester, NY.
authors.forename: Michael T
authors.initials: MT
authors.lastname: Milano
authors.affiliation: Department of Radiation Oncology, Instituto Madrileño de Oncología, Madrid, Spain.
authors.forename: Claudio V
authors.initials: CV
authors.lastname: Sole
authors.affiliation: Thoracic Oncology Division, European Institute of Oncology, Milan, Italy.
authors.forename: Tommaso M
authors.initials: TM
authors.lastname: De Pas
authors.affiliation: Department of Radiation Oncology, Rocky Mountain Cancer Centers, Aurora, CO.
authors.forename: Dennis L
authors.initials: DL
authors.lastname: Carter
authors.affiliation: Department of Radiation Oncology, London Health Sciences Centre, London, Ontario, Canada.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Warner
authors.affiliation: Department of Radiation Oncology, London Health Sciences Centre, London, Ontario, Canada. Electronic address: george.rodrigues@lhsc.on.ca.
authors.forename: George B
authors.initials: GB
authors.lastname: Rodrigues
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology / Q000628:therapy*; D002289:Carcinoma, Non-Small-Cell Lung / Q000473:pathology / Q000628:therapy*; D018572:Disease-Free Survival; D006801:Humans; D008175:Lung Neoplasms / Q000473:pathology / Q000628:therapy*; D009362:Neoplasm Metastasis; D011379:Prognosis; D016016:Proportional Hazards Models; D012306:Risk; D015996:Survival Rate
keywords: Metastectomy; NSCLC; Oligometastases; Radiotherapy; SABR/SBRT