title: Can 18F-FDG-PET response during radiotherapy be used as a predictive factor for the outcome of head and neck cancer patients?
abstract: OBJECTIVE
  We investigated if (18F) fluoro-2-deoxy-D-glucose positron emission tomography (F-FDG-PET) during radiotherapy or concurrent chemoradiotherapy adds information about the treatment outcome compared with an FDG-PET study before treatment.
  
  
  METHODS
  Forty-three patients with head and neck cancer were treated with helical tomotherapy. F-FDG-PET was performed at baseline and during the treatment after 47 Gy. Tracer accumulation at the tumor site was assessed visually and semiquantitatively using the maximal standardized uptake values (SUV(max)). With median SUV(max) of both the studies as cutoff, patients were categorized into low and high SUV(max) groups. For visual analysis, two independent observers classified patients as complete metabolic responders (CMR) or noncomplete metabolic responders (NCMR).
  
  
  RESULTS
  At baseline the median SUV(max) was 8.11 (2.41-15.13). The overall survival (OS) and disease-free survival (DFS) were 81 and 67% versus 50 and 40% for the low and high SUV(max), respectively. OS was significantly different (P=0.027). During therapy, median SUV(max) was 4.03 (1.94-7.58). OS and DFS were 82 and 63%, versus 47 and 42% for the low and high SUV(max) group, respectively. OS was significantly different (P=0.026). No significant differences between CMR versus NCMR in OS (72 vs. 60%), and DFS (56 vs. 49%) were found.
  
  
  CONCLUSIONS
  Categorizing patients on the basis of a semiquantitative approach resulted in significant differences in OS for both the scans before and during therapy. Future work on a larger number of patients is warranted to determine SUV(max) cutoff values which could be used for the early identification of patients with poor treatment outcome or perhaps other therapeutic approaches.
authors.affiliation: Department of aRadiation oncology, Oncologic Center UZ Brussel, Laarbeeklaan, Brussels, Belgium. darshraffarrag@yahoo.com
authors.forename: Ashraf
authors.initials: A
authors.lastname: Farrag
authors.forename: Gaëtane
authors.initials: G
authors.lastname: Ceulemans
authors.forename: Mia
authors.initials: M
authors.lastname: Voordeckers
authors.forename: Hendrik
authors.initials: H
authors.lastname: Everaert
authors.forename: Guy
authors.initials: G
authors.lastname: Storme
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001692:Biological Transport; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism; D006258:Head and Neck Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000532:radiotherapy* / Q000628:therapy; D006801:Humans; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D016019:Survival Analysis; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D019788:Fluorodeoxyglucose F18