title: Assessing the usefulness of 18F-fluorodeoxyglucose PET-CT scan after stereotactic body radiotherapy for early-stage non-small cell lung cancer.
abstract: BACKGROUND
  Although stereotactic body radiation therapy (SBRT) is an established treatment option for early-stage lung cancer, there are no guidelines for reassessing patients for local treatment failure or intrathoracic recurrence after treatment. This study reports the sensitivity, specificity, and positive and negative predictive values for 18F-fluorodeoxyglucose (FDG) PET-CT scanning when used to evaluate patients after SBRT.
  
  
  METHODS
  Charts were reviewed of all patients who received SBRT and a subsequent FDG PET-CT scan at a university hospital over a 5-year period. Pretreatment and 3-month posttreatment tumor characteristics on PET-CT scan and outcome data (adverse events from SBRT, need for repeat biopsy, rate of local treatment failure and recurrent disease, and all-cause mortality) were recorded.
  
  
  RESULTS
  Eighty-eight patients were included in the study. Fourteen percent of patients (12 of 88) had positive 3-month PET scans. Of the positive results, 67% (eight of 12) were true positives. Eighty-six percent (76 of 88 patients) had negative 3-month FDG PET-CT scans, with 89% (68 of 76) true negatives. FDG PET-CT scan performed 3 months after SBRT for non-small cell lung cancer (NSCLC) had a sensitivity of 50% (95% CI, 0.26-0.75), a specificity of 94% (95% CI, 0.89-1.0), a positive predictive value of 67% (95% CI, 0.4-0.93), and a negative predictive value of 89% (95% CI, 0.83- 0.96).
  
  
  CONCLUSIONS
  FDG PET-CT scan 3 months after treatment of NSCLC with SBRT was a specific but insensitive test for the detection of recurrence or treatment failure. Serial CT scans should be used for early surveillance following SBRT, whereas FDG PET-CT scans should be reserved to define suspected metastatic disease or to evaluate new abnormalities on CT scan, or for possible reassessment later in the follow-up period after radiation-related inflammation subsides.
authors.affiliation: Division of Pulmonary/Critical Care, Medical University of South Carolina, Charleston, SC. Electronic address: pastisn@musc.edu.
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Pastis
authors.affiliation: Division of Pulmonary/Critical Care, Medical University of South Carolina, Charleston, SC.
authors.forename: Travis J
authors.initials: TJ
authors.lastname: Greer
authors.affiliation: Division of Pulmonary/Critical Care, Medical University of South Carolina, Charleston, SC.
authors.forename: Nichole T
authors.initials: NT
authors.lastname: Tanner
authors.affiliation: Public Health Services, Medical University of South Carolina, Charleston, SC.
authors.forename: Amy E
authors.initials: AE
authors.lastname: Wahlquist
authors.affiliation: Department of Radiology, Medical University of South Carolina, Charleston, SC.
authors.forename: Leonie L
authors.initials: LL
authors.lastname: Gordon
authors.affiliation: Department of Radiation Oncology, Medical University of South Carolina, Charleston, SC.
authors.forename: Anand K
authors.initials: AK
authors.lastname: Sharma
authors.affiliation: Department of Radiation Oncology, Medical University of South Carolina, Charleston, SC.
authors.forename: Nicholas C
authors.initials: NC
authors.lastname: Koch
authors.affiliation: Division of Pulmonary/Critical Care, Medical University of South Carolina, Charleston, SC.
authors.forename: Gerard A
authors.initials: GA
authors.lastname: Silvestri
mesh_terms: D000328:Adult; D000368:Aged; D002289:Carcinoma, Non-Small-Cell Lung / Q000175:diagnosis* / Q000601:surgery; D042241:Early Diagnosis; D005260:Female; D019788:Fluorodeoxyglucose F18; D005500:Follow-Up Studies; D006801:Humans; D008175:Lung Neoplasms / Q000175:diagnosis* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D009367:Neoplasm Staging / Q000379:methods*; D049268:Positron-Emission Tomography / Q000379:methods*; D011184:Postoperative Period; D011379:Prognosis; D019275:Radiopharmaceuticals; D016634:Radiosurgery; D015203:Reproducibility of Results; D012189:Retrospective Studies; D013997:Time Factors; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18