title: Response monitoring by positron emission tomography during radiotherapy of a squamous cell skin carcinoma.
abstract: BACKGROUND
  Radiotherapy of skin cancer in a previously irradiated area is a challenging task with regard to cumulative total dose and consecutive normal tissue toxicity. Methods of biological response monitoring might be helpful in achieving a favorable therapeutic ratio.
  
  
  METHODS
  We report the case of a 77-year-old patient with squamous cell skin carcinoma originating within a previous radiotherapy field. Initially, the patient refused surgical resection. 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography (FDG-PET) was performed before re-irradiation and after 44 Gy.
  
  
  RESULTS
  FDG-PET showed no change in the standardized uptake value, i.e. no metabolic response. Clinically, the tumor failed to shrink after radiotherapy with a total dose of 64 Gy and progressed rapidly within the first 8 weeks of follow-up. Confirmatory biopsies were obtained and salvage surgery attempted.
  
  
  CONCLUSIONS
  In this case, FDG-PET after 44 Gy correctly identified a non-responding patient with squamous cell skin cancer. Thus, further assessment of this method for response evaluation and treatment optimization appears warranted.
authors.affiliation: Klinik und Poliklinik für Strahlentherapie und Radiologische Onkologie, Klinikum rechts der Isar der Technischen Universität München, Germany. cnied@hotmail.com
authors.forename: Carsten
authors.initials: C
authors.lastname: Nieder
authors.forename: Anca-Ligia
authors.initials: AL
authors.lastname: Grosu
mesh_terms: D000368:Aged; D002294:Carcinoma, Squamous Cell / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals; D011881:Radiotherapy, Computer-Assisted / Q000379:methods*; D012878:Skin Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D016896:Treatment Outcome
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18