title: Detection of Local Cancer Recurrence After Stereotactic Ablative Radiation Therapy for Lung Cancer: Physician Performance Versus Radiomic Assessment.
abstract: OBJECTIVE
  Stereotactic ablative radiation therapy (SABR) is a guideline-specified treatment option for early-stage lung cancer. However, significant posttreatment fibrosis can occur and obfuscate the detection of local recurrence. The goal of this study was to assess physician ability to detect timely local recurrence and to compare physician performance with a radiomics tool.
  
  
  METHODS
  Posttreatment computed tomography (CT) scans (n=182) from 45 patients treated with SABR (15 with local recurrence matched to 30 with no local recurrence) were used to measure physician and radiomic performance in assessing response. Scans were individually scored by 3 thoracic radiation oncologists and 3 thoracic radiologists, all of whom were blinded to clinical outcomes. Radiomic features were extracted from the same images. Performances of the physician assessors and the radiomics signature were compared.
  
  
  RESULTS
  When taking into account all CT scans during the whole follow-up period, median sensitivity for physician assessment of local recurrence was 83% (range, 67%-100%), and specificity was 75% (range, 67%-87%), with only moderate interobserver agreement (κ = 0.54) and a median time to detection of recurrence of 15.5 months. When determining the early prediction of recurrence within <6 months after SABR, physicians assessed the majority of images as benign injury/no recurrence, with a mean error of 35%, false positive rate (FPR) of 1%, and false negative rate (FNR) of 99%. At the same time point, a radiomic signature consisting of 5 image-appearance features demonstrated excellent discrimination, with an area under the receiver operating characteristic curve of 0.85, classification error of 24%, FPR of 24%, and FNR of 23%.
  
  
  CONCLUSIONS
  These results suggest that radiomics can detect early changes associated with local recurrence that are not typically considered by physicians. This decision support system could potentially allow for early salvage therapy of patients with local recurrence after SABR.
authors.affiliation: Department of Medical Biophysics, The University of Western Ontario, London, Ontario, Canada; Baines Imaging Research Laboratory, London Regional Cancer Program, London, Ontario, Canada.
authors.forename: Sarah A
authors.initials: SA
authors.lastname: Mattonen
authors.affiliation: Department of Medical Biophysics, The University of Western Ontario, London, Ontario, Canada; Baines Imaging Research Laboratory, London Regional Cancer Program, London, Ontario, Canada; Department of Oncology, The University of Western Ontario, London, Ontario, Canada. Electronic address: david.palma@lhsc.on.ca.
authors.forename: David A
authors.initials: DA
authors.lastname: Palma
authors.affiliation: Baines Imaging Research Laboratory, London Regional Cancer Program, London, Ontario, Canada.
authors.forename: Carol
authors.initials: C
authors.lastname: Johnson
authors.affiliation: Department of Oncology, The University of Western Ontario, London, Ontario, Canada.
authors.forename: Alexander V
authors.initials: AV
authors.lastname: Louie
authors.affiliation: Department of Diagnostic Radiology, London Health Sciences Centre, London, Ontario, Canada.
authors.forename: Mark
authors.initials: M
authors.lastname: Landis
authors.affiliation: Department of Oncology, The University of Western Ontario, London, Ontario, Canada.
authors.forename: George
authors.initials: G
authors.lastname: Rodrigues
authors.affiliation: Department of Diagnostic Radiology, London Health Sciences Centre, London, Ontario, Canada.
authors.forename: Ian
authors.initials: I
authors.lastname: Chan
authors.affiliation: Department of Diagnostic Radiology, London Health Sciences Centre, London, Ontario, Canada.
authors.forename: Roya
authors.initials: R
authors.lastname: Etemad-Rezai
authors.affiliation: Department of Medical Biophysics, The University of Western Ontario, London, Ontario, Canada; Baines Imaging Research Laboratory, London Regional Cancer Program, London, Ontario, Canada.
authors.forename: Timothy P C
authors.initials: TP
authors.lastname: Yeung
authors.affiliation: Department of Radiation Oncology, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Suresh
authors.initials: S
authors.lastname: Senan
authors.affiliation: Department of Medical Biophysics, The University of Western Ontario, London, Ontario, Canada; Baines Imaging Research Laboratory, London Regional Cancer Program, London, Ontario, Canada; Department of Oncology, The University of Western Ontario, London, Ontario, Canada.
authors.forename: Aaron D
authors.initials: AD
authors.lastname: Ward
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019540:Area Under Curve; D002289:Carcinoma, Non-Small-Cell Lung / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D002983:Clinical Competence; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging* / Q000473:pathology; D015588:Observer Variation; D049268:Positron-Emission Tomography; D012372:ROC Curve; D018787:Radiation Oncology; D011871:Radiology; D019275:Radiopharmaceuticals; D016634:Radiosurgery; D066066:Response Evaluation Criteria in Solid Tumors; D012680:Sensitivity and Specificity; D013997:Time Factors; D014057:Tomography, X-Ray Computed
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18