title: Surrogate Imaging Biomarkers of Response of Colorectal Liver Metastases After Salvage Radioembolization Using 90Y-Loaded Resin Microspheres.
abstract: OBJECTIVE
  The purpose of the present study is to evaluate Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1, tumor attenuation criteria, Choi criteria, and European Organization for Research and Treatment of Cancer (EORTC) PET criteria as measures of response and subsequent predictors of liver progression-free survival (PFS) after radioembolization (RE) of colorectal liver metastases (CLM). The study also assesses interobserver variability for measuring tumor attenuation using a single 2D ROI on a simple PACS workstation.
  
  
  METHODS
  We performed a retrospective review of the clinical RE database at our institution, to identify patients treated in the salvage setting for CLM between December 2009 and March 2013. Response was evaluated on FDG PET scans, with the use of EORTC PET criteria, and on portal venous phase CT scans, with the use of RECIST 1.1, tumor attenuation criteria, and Choi criteria. Two independent blinded observers measured tumor attenuation using a single 2D ROI. The intraclass correlation coefficient (ICC) for interobserver variability was assessed. Kaplan-Meier methodology was used to calculate liver PFS, and the log-rank test was used to assess the response criteria as predictors of liver PFS.
  
  
  RESULTS
  A total of 25 patients with 46 target tumors were enrolled in the study. The ICC was 0.95 at baseline and 0.98 at response evaluation. Among the 25 patients, more responders (i.e., partial response) were identified on the basis of EORTC PET criteria (n = 14), Choi criteria (n = 15), and tumor attenuation criteria (n = 13) than on the basis of RECIST 1.1 (n = 2). The median liver PFS was 3.0 months (95% CI, 2.1-4.0 months). Response identified on the basis of EORTC PET criteria (p < 0.001), Choi criteria (p < 0.001), or tumor attenuation criteria (p = 0.01) predicted liver PFS; however, response identified by RECIST 1.1 did not (p = 0.1).
  
  
  CONCLUSIONS
  RECIST 1.1 has poor sensitivity for detecting metabolic responses classified by EORTC PET criteria. EORTC PET criteria, Choi criteria, and tumor attenuation criteria appear to be equally reliable surrogate imaging biomarkers of liver PFS after RE in patients with CLM.
authors.affiliation: 1 Division of Interventional Radiology, Department of Radiology, Memorial Sloan Kettering Cancer Center, 1275 York Ave, Rm H-118, New York, NY 10065.
authors.forename: Waleed
authors.initials: W
authors.lastname: Shady
authors.affiliation: 1 Division of Interventional Radiology, Department of Radiology, Memorial Sloan Kettering Cancer Center, 1275 York Ave, Rm H-118, New York, NY 10065.
authors.forename: Vlasios S
authors.initials: VS
authors.lastname: Sotirchos
authors.affiliation: 2 Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY.
authors.forename: Richard K
authors.initials: RK
authors.lastname: Do
authors.affiliation: 3 Department of Nuclear Medicine, Memorial Sloan Kettering Cancer Center, New York, NY.
authors.forename: Neeta
authors.initials: N
authors.lastname: Pandit-Taskar
authors.affiliation: 3 Department of Nuclear Medicine, Memorial Sloan Kettering Cancer Center, New York, NY.
authors.forename: Jorge A
authors.initials: JA
authors.lastname: Carrasquillo
authors.affiliation: 4 Department of Epidemiology and Biostatistics, Memorial Sloan Kettering Cancer Center, New York, NY.
authors.forename: Mithat
authors.initials: M
authors.lastname: Gonen
authors.affiliation: 1 Division of Interventional Radiology, Department of Radiology, Memorial Sloan Kettering Cancer Center, 1275 York Ave, Rm H-118, New York, NY 10065.
authors.forename: Constantinos T
authors.initials: CT
authors.lastname: Sofocleous
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000032:analysis; D015179:Colorectal Neoplasms / Q000473:pathology*; D003287:Contrast Media; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008113:Liver Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy* / Q000556:secondary*; D008297:Male; D008863:Microspheres; D008875:Middle Aged; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D066066:Response Evaluation Criteria in Solid Tumors; D012189:Retrospective Studies; D016879:Salvage Therapy; D012680:Sensitivity and Specificity; D015996:Survival Rate; D014057:Tomography, X-Ray Computed; D015021:Yttrium Radioisotopes / Q000627:therapeutic use
chemical_list: D014408:Biomarkers, Tumor; D003287:Contrast Media; D019275:Radiopharmaceuticals; D015021:Yttrium Radioisotopes; D019788:Fluorodeoxyglucose F18
keywords: Choi criteria; colorectal liver metastases; radioembolization; tumor attenuation