title: Colorectal Histology Is Associated With an Increased Risk of Local Failure in Lung Metastases Treated With Stereotactic Ablative Radiation Therapy.
abstract: OBJECTIVE
  Stereotactic ablative radiation therapy (SABR) is increasingly used to treat lung oligometastases. We set out to determine the safety and efficacy of this approach and to identify factors associated with outcomes.
  
  
  METHODS
  We conducted a retrospective study of patients treated with SABR for metastatic lung tumors at our institution from 2003 to 2014. We assessed the association between various patient and treatment factors with local failure (LF), progression, subsequent treatment, systemic treatment, and overall survival (OS), using univariate and multivariate analyses.
  
  
  RESULTS
  We identified 122 tumors in 77 patients meeting inclusion criteria for this study. Median follow-up was 22 months. The 12- and 24-month cumulative incidence rates of LF were 8.7% and 16.2%, respectively; the 24-month cumulative incidence rates of progression, subsequent treatment, and subsequent systemic treatment were 75.2%, 64.5%, and 35.1%, respectively. Twenty-four-month OS was 74.6%, and median OS was 36 months. Colorectal metastases had a significantly higher cumulative incidence of LF at 12 and 24 months (25.5% and 42.2%, respectively), than all other histologies (4.4% and 9.9%, respectively; P<.0004). The 24-month cumulative incidences of LF for colorectal metastases treated with a biologically effective dose at α/β = 10 (BED10) of <100 Gy versus BED10 of ≥100 Gy were 62.5% and 16.7%, respectively (P=.08). Toxicity was minimal, with only a single grade 3 or higher event observed.
  
  
  CONCLUSIONS
  SABR for metastatic lung tumors appears to be safe and effective with excellent local control, treatment-free intervals, and OS. An exception is metastases from colorectal cancer, which have a high LF rate consistent with a radioresistant phenotype, suggesting a potential role for dose escalation.
authors.affiliation: Department of Radiation Oncology and Cancer Institute, Stanford University School of Medicine, Stanford, California.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Binkley
authors.affiliation: Department of Radiation Oncology, University of Southern California Keck School of Medicine, Los Angeles, California.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Trakul
authors.affiliation: Department of Radiation Oncology and Cancer Institute, Stanford University School of Medicine, Stanford, California.
authors.forename: Lisa Rose
authors.initials: LR
authors.lastname: Jacobs
authors.affiliation: Department of Radiation Oncology and Cancer Institute, Stanford University School of Medicine, Stanford, California.
authors.forename: Rie
authors.initials: R
authors.lastname: von Eyben
authors.affiliation: Department of Radiation Oncology and Cancer Institute, Stanford University School of Medicine, Stanford, California.
authors.forename: Quynh-Thu
authors.initials: QT
authors.lastname: Le
authors.affiliation: Department of Radiation Oncology and Cancer Institute, Stanford University School of Medicine, Stanford, California.
authors.forename: Peter G
authors.initials: PG
authors.lastname: Maxim
authors.affiliation: Department of Radiation Oncology and Cancer Institute, Stanford University School of Medicine, Stanford, California.
authors.forename: Billy W
authors.initials: BW
authors.lastname: Loo
authors.affiliation: Department of Radiation Oncology and Cancer Institute, Stanford University School of Medicine, Stanford, California. Electronic address: DavidS4@Stanford.edu.
authors.forename: David Benjamin
authors.initials: DB
authors.lastname: Shultz
authors.affiliation: Department of Radiation Oncology and Cancer Institute, Stanford University School of Medicine, Stanford, California; Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, California. Electronic address: Diehn@Stanford.edu.
authors.forename: Maximilian
authors.initials: M
authors.lastname: Diehn
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D003110:Colonic Neoplasms / Q000473:pathology*; D018450:Disease Progression; D019583:Dose Fractionation, Radiation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008175:Lung Neoplasms / Q000401:mortality / Q000473:pathology / Q000556:secondary* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D009928:Organ Specificity; D016634:Radiosurgery / Q000379:methods* / Q000401:mortality; D012004:Rectal Neoplasms / Q000473:pathology*; D012189:Retrospective Studies; D012509:Sarcoma / Q000401:mortality / Q000473:pathology / Q000556:secondary / Q000601:surgery; D013997:Time Factors; D016896:Treatment Outcome