title: Impact of inadequate respiratory motion management in SBRT for oligometastatic colorectal cancer.
abstract: OBJECTIVE
  Stereotactic body radiotherapy (SBRT) in oligometastatic colorectal cancer (CRC) resulted in a disappointing 1-year local control rate of 54% in our experience. We aimed to determine the root cause(s).
  
  
  METHODS
  47 oligometastatic CRC patients were treated with SBRT by helical tomotherapy to a dose of 40 or 50Gy in 10 fractions, without specific respiratory motion management and PTV-margins of 10-10-12mm in all patients. The local recurrences (LRs) were delineated on diagnostic PET-CT scans and co-registered with initial planning CTs. LRs were classified as in-field or marginal with respect to the initial dose distribution, and predictors for LR were determined.
  
  
  RESULTS
  Out of 105 irradiated metastases, LR modeling yielded 15 in-field and 15 marginal failures. Metastases in moving organs (liver and lung) exhibited a local control of 53% at 1-year (95% confidence interval (CI): 38-67%), compared to 79% for lymph nodes (95% CI: 32-95%). The first group exhibited a sixfold increased risk compared to the latter on multivariate analysis (p=0.01).
  
  
  CONCLUSIONS
  The nature and locations of LR indicated that dose prescription and methodology were both inadequate for liver and lung metastases. This study demonstrates the need for individual respiratory motion management and a biological effective dose of >75Gy.
authors.affiliation: Department of Radiotherapy, Universitair Ziekenhuis Brussel (UZ Brussel), Vrije Universiteit Brussel (VUB), Belgium.
authors.forename: Robbe
authors.initials: R
authors.lastname: Van den Begin
authors.affiliation: Department of Radiotherapy, Universitair Ziekenhuis Brussel (UZ Brussel), Vrije Universiteit Brussel (VUB), Belgium. Electronic address: benedikt.engels@gmail.com.
authors.forename: Benedikt
authors.initials: B
authors.lastname: Engels
authors.affiliation: Department of Radiotherapy, Universitair Ziekenhuis Brussel (UZ Brussel), Vrije Universiteit Brussel (VUB), Belgium.
authors.forename: Thierry
authors.initials: T
authors.lastname: Gevaert
authors.affiliation: Department of Radiotherapy, Universitair Ziekenhuis Brussel (UZ Brussel), Vrije Universiteit Brussel (VUB), Belgium.
authors.forename: Michaël
authors.initials: M
authors.lastname: Duchateau
authors.affiliation: Department of Radiotherapy, Universitair Ziekenhuis Brussel (UZ Brussel), Vrije Universiteit Brussel (VUB), Belgium.
authors.forename: Koen
authors.initials: K
authors.lastname: Tournel
authors.affiliation: Department of Radiotherapy, Universitair Ziekenhuis Brussel (UZ Brussel), Vrije Universiteit Brussel (VUB), Belgium.
authors.forename: Dirk
authors.initials: D
authors.lastname: Verellen
authors.affiliation: Department of Radiotherapy, Universitair Ziekenhuis Brussel (UZ Brussel), Vrije Universiteit Brussel (VUB), Belgium.
authors.forename: Guy
authors.initials: G
authors.lastname: Storme
authors.affiliation: Department of Radiotherapy, Universitair Ziekenhuis Brussel (UZ Brussel), Vrije Universiteit Brussel (VUB), Belgium.
authors.forename: Mark
authors.initials: M
authors.lastname: De Ridder
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015179:Colorectal Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D005260:Female; D006801:Humans; D008113:Liver Neoplasms / Q000532:radiotherapy / Q000556:secondary; D008175:Lung Neoplasms / Q000532:radiotherapy / Q000556:secondary; D008297:Male; D008875:Middle Aged; D009068:Movement; D011829:Radiation Dosage; D016634:Radiosurgery / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated; D012008:Recurrence; D012119:Respiration
keywords: Colorectal cancer; Local control; Local failure; Motion management; Oligometastases; SBRT