title: The Role of FDG-PET in the Initial Staging and Response Assessment of Anal Cancer: A Systematic Review and Meta-analysis.
abstract: OBJECTIVE
  The aim of this systematic review and meta-analysis was to compare the role of FDG-positron emission tomography (PET) or PET/computed tomography (CT) with conventional imaging in the detection of primary and nodal disease in anal cancer, and to assess the impact of PET or PET/CT on the management of anal cancer.
  
  
  METHODS
  A systematic review of the literature was performed. Eligible studies included those comparing PET or PET/CT with conventional imaging in the staging of histologically confirmed anal squamous cell carcinoma (SCC), or studies that performed PET or PET/CT imaging to assess response following treatment.
  
  
  RESULTS
  Twelve studies met the inclusion criteria. For the detection of primary disease, CT and PET had a sensitivity of 60 % (95 % confidence interval [CI] 45.5-75.2) and 99 % (95 % CI 96-100), respectively. Compared with conventional imaging, PET upstaged 15 % (95 % CI 10-21) and downstaged 15 % (95 % CI 10-20) of nodal disease. This led to a change in nodal staging in 28 % of patients (95 % CI 18-38). When only studies performing contemporary PET/CT were considered, the rate of nodal upstaging was 21 % (95 % CI 13-30) and the TNM stage was altered in 41 % of patients. Following chemoradiotherapy, 78 % (95 % CI 65-88) of patients had a complete response on PET.
  
  
  CONCLUSIONS
  Compared with conventional imaging, PET or PET/CT alters the nodal status in a sufficient number of cases to justify its routine use in the staging of patients with anal SCC.
authors: Department of Radiation Oncology, Royal Prince Alfred Hospital, Camperdown, Australia. mpjones85@gmail.com.
authors: Michael
authors: M
authors: Jones
authors: Department of Radiation Oncology, Royal Prince Alfred Hospital, Camperdown, Australia.
authors: George
authors: G
authors: Hruby
authors: Department of Surgery, Royal Prince Alfred Hospital, Camperdown, Australia.
authors: Michael
authors: M
authors: Solomon
authors: Department of Nuclear Medicine, Calvary Mater Newcastle, Waratah, Australia.
authors: Natalie
authors: N
authors: Rutherford
authors: Department of Radiation Oncology, Calvary Mater Newcastle, Waratah, Australia.
authors: Jarad
authors: J
authors: Martin
mesh_terms: D001005:Anus Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000628:therapy; D002294:Carcinoma, Squamous Cell / Q000000981:diagnostic imaging* / Q000556:secondary / Q000628:therapy; D059248:Chemoradiotherapy; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008207:Lymphatic Metastasis; D064847:Multimodal Imaging; D009367:Neoplasm Staging; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18