title: Stereotactic body radiotherapy for colorectal liver metastases: a pooled analysis.
abstract: BACKGROUND
  This study was undertaken to determine outcomes of stereotactic body radiotherapy for colorectal liver metastases in a pooled patient cohort.
  
  
  METHODS
  Patients with colorectal liver metastases from 3 institutions were included if they had 1 to 4 lesions, received 1 to 6 fractions of stereotactic body radiotherapy, and had radiologic imaging ≥ 3 months post-treatment. Sixty-five patients with 102 lesions treated from August 2003 to May 2009 were retrospectively analyzed. A tumor control probability (TCP) model was used to estimate the 3-fraction dose required for > 90% local control after converting the schedule into biologically equivalent dose (BED), single-fraction equivalent dose, or linear quadratic model-based single-fraction dose.
  
  
  RESULTS
  Forty-seven (72%) patients had ≥ 1 chemotherapy regimen before stereotactic body radiotherapy, and 27 (42%) patients had ≥ 2 regimens. The median follow-up was 1.2 years (range, 0.3-5.2 years). The median dose was 42 gray (Gy; range, 22-60 Gy). When evaluated separately by multivariate analysis, total dose (P = .0015), dose/fraction (P = .003), and BED (P = .004) all correlated with local control by lesion. On multivariate analysis, nonactive extrahepatic disease was associated with overall survival (OS; P = .046), and sustained local control was closely correlated (P = .06). By using single-fraction equivalent dose, BED, or linear quadratic model-based single-fraction dose in the TCP model, the estimated dose range needed for 1-year local control > 90% is 46 to 52 Gy in 3 fractions.
  
  
  CONCLUSIONS
  Liver stereotactic body radiotherapy is well tolerated and effective for colorectal liver metastases. The strong correlation between local control and OS supports controlling hepatic disease even for heavily pretreated patients. For a 3-fraction regimen of stereotactic body radiotherapy, a prescription dose of ≥ 48 Gy should be considered, if normal tissue constraints allow.
authors: Department of Radiation Oncology, Stanford University, Stanford, California, USA. dtchang@stanford.edu
authors: Daniel T
authors: DT
authors: Chang
authors: Anand
authors: A
authors: Swaminath
authors: Margaret
authors: M
authors: Kozak
authors: Julie
authors: J
authors: Weintraub
authors: Albert C
authors: AC
authors: Koong
authors: John
authors: J
authors: Kim
authors: Rob
authors: R
authors: Dinniwell
authors: James
authors: J
authors: Brierley
authors: Brian D
authors: BD
authors: Kavanagh
authors: Laura A
authors: LA
authors: Dawson
authors: Tracey E
authors: TE
authors: Schefter
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015179:Colorectal Neoplasms / Q000473:pathology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008113:Liver Neoplasms / Q000532:radiotherapy* / Q000556:secondary; D008297:Male; D008875:Middle Aged; D016634:Radiosurgery / Q000009:adverse effects / Q000379:methods*; D011879:Radiotherapy Dosage; D016896:Treatment Outcome