title: Predictors of Chest Wall Toxicity after Lung Stereotactic Ablative Radiotherapy.
abstract: OBJECTIVE
  To determine the incidence and predictive factors of rib fracture and chest wall pain after lung stereotactic ablative radiotherapy (SABR).
  
  
  METHODS
  Patients were treated with lung SABR of 48-60 Gy in four to five fractions. The treatment plan and follow-up computed tomography scans of 289 tumours in 239 patients were reviewed. Dose-volume histogram (DVH) metrics and clinical factors were evaluated as potential predictors of chest wall toxicity.
  
  
  RESULTS
  The median follow-up was 21.0 months (range 6.2-52.1). Seventeen per cent (50/289) developed a rib fracture, 44% (22/50) were symptomatic; the median time to fracture was 16.4 months. On univariate analysis, female gender, osteoporosis, tumours adjacent (within 5 mm) to the chest wall and all of the chest wall DVH metrics predicted for rib fracture, but only tumour location adjacent to the chest wall remained significant on the multivariate model (P < 0.01). The 2 year fracture-free probability for those adjacent to the chest wall was 65.6%. Among those tumours adjacent to the chest wall, only osteoporosis (P = 0.02) predicted for fracture, whereas none of the chest wall DVH metrics were predictive. Eight per cent (24/289) experienced chest wall pain without fracture.
  
  
  CONCLUSIONS
  None of the chest wall DVH metrics independently predicted for SABR-induced rib fracture when tumour location is taken into account. Patients with tumours adjacent (within 5 mm) to the chest wall are at greater risk of rib fracture after lung SABR, and among these, an additional risk was observed in osteoporotic patients.
authors.affiliation: Sunnybrook Odette Cancer Centre, Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Canada.
authors.forename: I
authors.initials: I
authors.lastname: Thibault
authors.affiliation: Sunnybrook Odette Cancer Centre, Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Canada.
authors.forename: A
authors.initials: A
authors.lastname: Chiang
authors.affiliation: Sunnybrook Odette Cancer Centre, Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Canada.
authors.forename: D
authors.initials: D
authors.lastname: Erler
authors.affiliation: Department of Paediatrics and Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, Ontario, Canada.
authors.forename: L
authors.initials: L
authors.lastname: Yeung
authors.affiliation: Sunnybrook Odette Cancer Centre, Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Canada.
authors.forename: I
authors.initials: I
authors.lastname: Poon
authors.affiliation: Sunnybrook Odette Cancer Centre, Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Canada.
authors.forename: A
authors.initials: A
authors.lastname: Kim
authors.affiliation: Sunnybrook Odette Cancer Centre, Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Canada.
authors.forename: B
authors.initials: B
authors.lastname: Keller
authors.affiliation: Sunnybrook Odette Cancer Centre, Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Canada.
authors.forename: F
authors.initials: F
authors.lastname: Lochray
authors.affiliation: Centre for Cancer Research and Cell Biology, Queen's University Belfast, Belfast, UK.
authors.forename: S
authors.initials: S
authors.lastname: Jain
authors.affiliation: Sunnybrook Odette Cancer Centre, Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Canada.
authors.forename: H
authors.initials: H
authors.lastname: Soliman
authors.affiliation: Sunnybrook Odette Cancer Centre, Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Canada. Electronic address: Patrick.Cheung@sunnybrook.ca.
authors.forename: P
authors.initials: P
authors.lastname: Cheung
mesh_terms: D000328:Adult; D000369:Aged, 80 and over; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D015994:Incidence; D008175:Lung Neoplasms / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011832:Radiation Injuries / Q000453:epidemiology / Q000209:etiology*; D016634:Radiosurgery / Q000009:adverse effects* / Q000379:methods; D012253:Rib Fractures / Q000209:etiology*; D012307:Risk Factors; D035441:Thoracic Wall / Q000528:radiation effects; D014057:Tomography, X-Ray Computed / Q000009:adverse effects
keywords: Chest wall pain; lung cancer; lung metastases; rib fracture; stereotactic body radiotherapy