title: Retrospective review of positron emission tomography with contrast-enhanced computed tomography in the posttreatment setting in human papillomavirus-associated oropharyngeal carcinoma.
abstract: OBJECTIVE
  To determine the value of positron emission tomography (PET) with contrast-enhanced computed tomography (CT) in assessing the need for neck dissection by retrospectively reviewing the pathology reports of patients with human papillomavirus (HPV)-associated oropharyngeal squamous cell carcinoma (SCC).
  
  
  METHODS
  Retrospective cohort study.
  
  
  METHODS
  Tertiary medical center.
  
  
  METHODS
  Seventy-seven patients with HPV-related SCC.
  
  
  METHODS
  Seventy-seven consecutive patients with a diagnosis of HPV-related SCC who were treated with radiotherapy as the primary treatment between August 2007 and October 2010 were retrospectively evaluated for radiologic and pathologic rate of persistence of nodal metastasis after completion of definitive radiotherapy. Pretreatment and posttreatment imaging included contrast-enhanced CT and PET. Response to treatment was measured on CT, PET at standardized uptake value (SUV) thresholds of 2 and 2.5, and PET/CT by a neuroradiologist in a blinded fashion. Then, the pathology report of the patients who underwent neck dissections was reviewed for nodal status after resection and correlated with the imaging findings.
  
  
  RESULTS
  Of the 77 patients, 67 met the study criteria, with an average follow-up PET/CT scan at 90.5 days after completion of radiotherapy. Ten patients did not undergo follow-up PET/CT imaging. Twenty patients underwent neck dissections after completion of radiation therapy. Of these 20 patients, 4 had persistent tumor and 16 did not have viable tumor. Using the final pathology report to correlate with imaging responses, CT had a negative predictive value (NPV) of 85.7% (95% CI, 48.7%-97.4%), PET with SUV thresholds of 2 had an NPV of 91.7% (95% CI, 64.6%-98.5%), PET with a cutoff SUV of 2.5 had an NPV of 85.7% (95% CI, 60.1%-96.0%), PET/CT with an SUV of 2 had an NPV of 100% (95% CI, 59.8%-100.0%), and PET/CT with an SUV of 2.5 had an NPV of 85.7% (95% CI, 48.7%-97.4%). The 47 patients who did not undergo neck dissection had a median follow-up of 26 months without an isolated neck failure. Analysis of all 67 patients in the cohort revealed the following values: CT had an NPV of 95.7% (95% CI, 85.8%-98.8%), PET with an SUV of 2 had an NPV of 98.2% (95% CI, 90.4%-99.7%), PET with an SUV of 2.5 had an NPV of 95.0% (95% CI, 86.3%-98.3%), PET/CT with an SUV of 2 had an NPV of 100.0% (95% CI, 92.0%-100.0%), and PET/CT with an SUV of 2.5 had an NPV of 95.7% (95% CI, 85.8%-98.8%).
  
  
  CONCLUSIONS
  Positron emission tomography combined with contrast-enhanced CT has a better NPV than either imaging modality alone in patients with HPV-associated oropharyngeal SCC. Furthermore, PET/CT with an SUV threshold of 2 used in patients with HPV-related SCC offers an imaging modality with a high NPV that may obviate the need for unnecessary neck dissections.
authors.forename: Jason Y K
authors.initials: JY
authors.lastname: Chan
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Sanguineti
authors.forename: Jeremy D
authors.initials: JD
authors.lastname: Richmon
authors.forename: Shanthi
authors.initials: S
authors.lastname: Marur
authors.forename: Christine G
authors.initials: CG
authors.lastname: Gourin
authors.forename: Wayne
authors.initials: W
authors.lastname: Koch
authors.forename: Christine H
authors.initials: CH
authors.lastname: Chung
authors.forename: Harry
authors.initials: H
authors.lastname: Quon
authors.forename: Justin A
authors.initials: JA
authors.lastname: Bishop
authors.forename: Nafi
authors.initials: N
authors.lastname: Aygun
authors.forename: Nishant
authors.initials: N
authors.lastname: Agrawal
mesh_terms: D000328:Adult; D000368:Aged; D002294:Carcinoma, Squamous Cell / Q000000981:diagnostic imaging* / Q000401:mortality / Q000532:radiotherapy / Q000601:surgery / Q000821:virology; D015331:Cohort Studies; D003287:Contrast Media; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D037981:Neck Dissection / Q000379:methods* / Q000401:mortality; D009361:Neoplasm Invasiveness / Q000473:pathology; D009367:Neoplasm Staging; D009959:Oropharyngeal Neoplasms / Q000000981:diagnostic imaging* / Q000401:mortality / Q000532:radiotherapy / Q000601:surgery / Q000821:virology; D030361:Papillomavirus Infections / Q000000981:diagnostic imaging* / Q000401:mortality / Q000473:pathology; D049268:Positron-Emission Tomography / Q000379:methods*; D011237:Predictive Value of Tests; D011379:Prognosis; D011882:Radiotherapy, High-Energy / Q000379:methods; D012189:Retrospective Studies; D018570:Risk Assessment; D016019:Survival Analysis; D062606:Tertiary Care Centers; D014057:Tomography, X-Ray Computed / Q000379:methods
chemical_list: D003287:Contrast Media