title: (18)F-FDG PET/CT to assess response and guide risk-stratified follow-up after chemoradiotherapy for oropharyngeal squamous cell carcinoma.
abstract: OBJECTIVE
  To evaluate the use of (18)F-FDG PET/CT as the principal investigation to assess tumour response, to determine the need for further surgery and to guide follow-up following radical chemoradiotherapy for stage III/IV oropharyngeal squamous cell carcinoma (OPSCC).
  
  
  METHODS
  A retrospective analysis was undertaken in 146 patients treated at our centre with radical chemoradiotherapy for OPSCC and who had a PET/CT scan to assess response. According to the PET/CT findings, patients were divided into four groups and recommendations: (1) complete metabolic response (enter clinical follow-up); (2) low-level uptake only (follow-up PET/CT scan in 12 weeks); (3) residual uptake suspicious for residual disease (further investigation with or without neck dissection); and (4) new diagnosis of distant metastatic disease (palliative treatment options).
  
  
  RESULTS
  The initial PET/CT scan was performed at a median of 12.4 weeks (range 4.3 - 21.7 weeks) following treatment. Overall sensitivity and specificity rates were 92.0 % (74.0 - 99.0 %) and 85 % (77.5 - 90.9 %). Of the 146 patients, 90 (62 %) had a complete response and had estimated 3-year overall and disease-free survival rates of 91.9 % (85.6 - 98.2 %) and 85.6 % (78.0 - 93.2 %), respectively, 17 (12 %) had residual low-level uptake only (with two having confirmed residual disease on subsequent PET/CT, both surgically salvaged), 30 (21 %) had suspicious residual uptake (12 proceeded to neck dissection; true positive rate at surgery 33 %). HPV-positive patients with reassuring PET/CT findings had an estimated 3-year progression-free survival rate of 91.7 % (85.2 - 98.2 %), compared with 66.2 % (41.5 - 90.9 %) of HPV-negative patients.
  
  
  CONCLUSIONS
  A strategy of using PET/CT results alongside clinical examination to help select patients for salvage surgery appears successful. Despite a complete response on the 12-week PET/CT scan, HPV-negative patients have a significant risk of disease relapse in the following 2 years and further studies to assess whether surveillance imaging in this group could improve outcomes are warranted.
authors.affiliation: Department of Clinical Oncology, Guy's and St Thomas' NHS Foundation Trust, London, UK. Thomas.Bird@nhs.net.
authors.forename: Thomas
authors.initials: T
authors.lastname: Bird
authors.affiliation: PET Imaging Centre at St Thomas' Hospital, King's College, London, UK.
authors.forename: Sally
authors.initials: S
authors.lastname: Barrington
authors.affiliation: Head and Neck Pathology Department, Guy's and St Thomas' NHS Foundation Trust, London, UK.
authors.forename: Selvam
authors.initials: S
authors.lastname: Thavaraj
authors.affiliation: Department of Head & Neck Surgery, Guy's and St Thomas' NHS Foundation Trust, London, UK.
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Jeannon
authors.affiliation: Department of Head & Neck Surgery, Guy's and St Thomas' NHS Foundation Trust, London, UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: Lyons
authors.affiliation: Department of Head & Neck Surgery, Guy's and St Thomas' NHS Foundation Trust, London, UK.
authors.forename: Richard
authors.initials: R
authors.lastname: Oakley
authors.affiliation: Department of Head & Neck Surgery, Guy's and St Thomas' NHS Foundation Trust, London, UK.
authors.forename: Ricard
authors.initials: R
authors.lastname: Simo
authors.affiliation: Department of Clinical Oncology, Guy's and St Thomas' NHS Foundation Trust, London, UK.
authors.forename: Mary
authors.initials: M
authors.lastname: Lei
authors.affiliation: Department of Clinical Oncology, Guy's and St Thomas' NHS Foundation Trust, London, UK.
authors.forename: Teresa
authors.initials: T
authors.lastname: Guerrero Urbano
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001692:Biological Transport; D002294:Carcinoma, Squamous Cell / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology / Q000628:therapy*; D059248:Chemoradiotherapy; D018572:Disease-Free Survival; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009959:Oropharyngeal Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology / Q000628:therapy*; D000072078:Positron Emission Tomography Computed Tomography; D012189:Retrospective Studies; D018570:Risk Assessment; D016896:Treatment Outcome
chemical_list: D019788:Fluorodeoxyglucose F18
keywords: Chemoradiotherapy; Human papillomavirus; Neck dissection; Otorhinolaryngological neoplasms; Positron emission tomography