title: Lack of clinical impact of18F-fluorodeoxyglucose positron emission tomography with simultaneous computed tomography for stage I and II Merkel cell carcinoma with concurrent sentinel lymph node biopsy staging: A single institutional experience from Westmead Hospital, Sydney.
abstract: OBJECTIVE
  18F-fluorodeoxyglucose (FDG) positron emission tomography with simultaneous computed tomography (PET-CT) FDG PET-CT plays an important clinical role in the staging and management of Merkel cell carcinoma (MCC) although its role in stage I and II disease relative to a sentinel lymph node biopsy (SLNB) is undefined. This study aimed to compare the clinical impact of FDG PET-CT and SLNB on management in stage I and II MCC.
  
  
  METHODS
  This was a retrospective observational study. Between 2000 and 2014, 65 patients with biopsy-proven MCC (all stages) underwent a staging FDG PET-CT as part of their investigations in Westmead Hospital, Sydney. Since 2006, 26 patients have had an SLNB and of these, 16 underwent both an SLNB and FDGPET-CT. All 16 patients had a histological diagnosis consistent with MCC without clinical evidence of regional or distant metastases prior to SLNB and FDG PET-CT (stages IB and IIB). These patients were assessed with respect to MCC staging and the subsequent change of patient management post-SLNB and FDG PET-CT.
  
  
  RESULTS
  The SLNB identified occult lymph node metastases in 10 patients (63%), with FDG PET-CT positive in only one patient (6%). Of the six SLNB-negative patients, none demonstrated additional metastases on the FDG PET-CT.
  
  
  CONCLUSIONS
  In patients with stage I and II MCC, FDG PET-CT is less sensitive than an SLNB in detecting occult metastatic lymph nodes. The routine use of FDG PET-CT in these patients may not be justified.
authors.affiliation: Department of Nuclear Medicine and Ultrasound, Westmead Hospital, Sydney, New South Wales, Australia.
authors.forename: Jui
authors.initials: J
authors.lastname: Liu
authors.affiliation: Department of Nuclear Medicine and Ultrasound, Westmead Hospital, Sydney, New South Wales, Australia.|Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia.
authors.forename: George
authors.initials: G
authors.lastname: Larcos
authors.affiliation: Department of Surgical Oncology, Westmead Hospital, Sydney, New South Wales, Australia.
authors.forename: Julie
authors.initials: J
authors.lastname: Howle
authors.affiliation: Department of Radiation Oncology, Westmead Cancer Care Centre, Westmead Hospital, Sydney, New South Wales, Australia.|Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia.
authors.forename: Michael
authors.initials: M
authors.lastname: Veness
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001315:Australia; D015266:Carcinoma, Merkel Cell / Q000000981:diagnostic imaging / Q000556:secondary; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008198:Lymph Nodes / Q000000981:diagnostic imaging* / Q000473:pathology; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D000072078:Positron Emission Tomography Computed Tomography; D019275:Radiopharmaceuticals; D012189:Retrospective Studies; D021701:Sentinel Lymph Node Biopsy; D012878:Skin Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
keywords: FDG PET-CT; Merkel cell carcinoma; sentinel lymph node biopsy