title: Early prediction by 18F-FDG PET/CT for progression-free survival and overall survival in patients with metastatic colorectal cancer receiving third-line cetuximab-based therapy.
abstract: OBJECTIVE
  In metastatic colorectal cancer (mCRC) with wild-type K-ras, cetuximab-based regimen is an option for third-line therapy. The objective of this study was to assess if early response evaluation by 18F-FDG PET/CT can predict progression-free survival (PFS) and overall survival (OS) in these patients.
  
  
  METHODS
  Patients with mCRC going to receive third-line cetuximab-based therapy were enrolled. 18F-FDG PET/CT studies were arranged at baseline and at the ends of the first and fourth weeks of therapy. Treatment response was evaluated with 2 methods: method 1 based on PET response criteria in solid tumors 1.0 and method 2 based on the assumption that an increase in peak tumor metabolism implies nonresponse. Progression-free survival was counted to tumor progression based on the Response Evaluation Criteria in Solid Tumors 1.1 or death. The predictive powers for PFS and OS were analyzed using the Kaplan-Meier method and the log-rank test.
  
  
  RESULTS
  Twenty-seven patients were eligible with a median PFS of 5.8 months and a median OS of 9.1 months. Method 2 predicts PFS (P = 0.001) and OS (P < 0.001) at the end of the first week, whereas method 1 does not. Both methods predict PFS and OS at the end of the fourth week.
  
  
  CONCLUSIONS
  Early response evaluation by 18F-FDG PET/CT predicts PFS and OS in patients with mCRC receiving third-line cetuximab-based therapy. Early therapeutic change may be possible for nonresponsive patients after 1 week of treatment.
authors.affiliation: From the *Department of Nuclear Medicine and Molecular Imaging Center, †Division of Colon and Rectal Surgery, Department of Surgery, and ‡Division of Hematology/Oncology, Department of Internal Medicine, Chang Gung Memorial Hospital at Linkou, Chang Gung University College of Medicine, Taoyuan, Taiwan.
authors.forename: Feng-Yuan
authors.initials: FY
authors.lastname: Liu
authors.forename: Tzu-Chen
authors.initials: TC
authors.lastname: Yen
authors.forename: Jeng-Yi
authors.initials: JY
authors.lastname: Wang
authors.forename: Tsai-Sheng
authors.initials: TS
authors.lastname: Yang
mesh_terms: D000328:Adult; D000368:Aged; D061067:Antibodies, Monoclonal, Humanized / Q000627:therapeutic use*; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D000068818:Cetuximab; D015179:Colorectal Neoplasms / Q000000981:diagnostic imaging* / Q000188:drug therapy / Q000401:mortality / Q000473:pathology; D018572:Disease-Free Survival; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D009362:Neoplasm Metastasis; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
chemical_list: D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D000068818:Cetuximab