title: Residual ¹⁸F-FDG-PET uptake 12 weeks after stereotactic ablative radiotherapy for stage I non-small-cell lung cancer predicts local control.
abstract: OBJECTIVE
  To investigate the prognostic value of [(18)F]fluorodeoxyglucose positron emission tomography (FDG-PET) uptake at 12 weeks after stereotactic ablative radiotherapy (SABR) for stage I non-small-cell lung cancer (NSCLC).
  
  
  METHODS
  From November 2006 to February 2010, 132 medically inoperable patients with proven Stage I NSCLC or FDG-PET-positive primary lung tumors were analyzed retrospectively. SABR consisted of 60 Gy delivered in 3 to 8 fractions. Maximum standardized uptake value (SUV(max)) of the treated lesion was assessed 12 weeks after SABR, using FDG-PET. Patients were subsequently followed at regular intervals using computed tomography (CT) scans. Association between post-SABR SUV(max) and local control (LC), mediastinal failure, distant failure, overall survival (OS), and disease-specific survival (DSS) was examined.
  
  
  RESULTS
  Median follow-up time was 17 months (range, 3-40 months). Median lesion size was 25 mm (range, 9-70 mm). There were 6 local failures: 15 mediastinal failures, 15 distant failures, 13 disease-related deaths, and 16 deaths from intercurrent diseases. Glucose corrected post-SABR median SUV(max) was 3.0 (range, 0.55-14.50). Using SUV(max) 5.0 as a cutoff, the 2-year LC was 80% versus 97.7% for high versus low SUV(max), yielding an adjusted subhazard ratio (SHR) for high post-SABR SUV(max) of 7.3 (95% confidence interval [CI], 1.4-38.5; p = 0.019). Two-year DSS rates were 74% versus 91%, respectively, for high and low SUV(max) values (SHR, 2.2; 95% CI, 0.8-6.3; p = 0.113). Two-year OS was 62% versus 81% (hazard ratio [HR], 1.6; 95% CI, 0.7-3.7; p = 0.268).
  
  
  CONCLUSIONS
  Residual FDG uptake (SUV(max) ≥5.0) 12 weeks after SABR signifies increased risk of local failure. A single FDG-PET scan at 12 weeks could be used to tailor further follow-up according to the risk of failure, especially in patients potentially eligible for salvage surgery.
authors.affiliation: Department of Radiation Oncology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands. v.r.bollineni@umcg.nl
authors.forename: Vikram Rao
authors.initials: VR
authors.lastname: Bollineni
authors.forename: Joachim
authors.initials: J
authors.lastname: Widder
authors.forename: Jan
authors.initials: J
authors.lastname: Pruim
authors.forename: Johannes A
authors.initials: JA
authors.lastname: Langendijk
authors.forename: Erwin M
authors.initials: EM
authors.lastname: Wiegman
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002289:Carcinoma, Non-Small-Cell Lung / Q000000981:diagnostic imaging* / Q000401:mortality / Q000473:pathology / Q000556:secondary / Q000601:surgery; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000401:mortality / Q000473:pathology / Q000601:surgery; D008297:Male; D008479:Mediastinal Neoplasms / Q000000981:diagnostic imaging / Q000556:secondary; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging*; D049268:Positron-Emission Tomography / Q000379:methods; D011379:Prognosis; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D016634:Radiosurgery / Q000379:methods*; D016019:Survival Analysis; D013997:Time Factors; D047368:Tumor Burden
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18