title: Lung stereotactic body radiation therapy: regional nodal failure is not predicted by tumor size.
abstract: BACKGROUND
  To examine regional nodal failure patterns with respect to lesion size in medically inoperable early-stage non-small cell lung cancer (NSCLC) patients treated with definitive lung stereotactic body radiation therapy (SBRT).
  
  
  METHODS
  Between 2004 and 2012, 342 medically inoperable early-stage NSCLC patients treated with definitive SBRT were identified in our institutional review board-approved prospective registry. All patients were treated on a Novalis/BrainLAB system using ExacTrac for image guidance. Kaplan-Meier analysis was performed with the log-rank test used to detect differences between lesion size and nodal failure patterns. Cox-proportional hazard regression analysis was performed to identify predictors of nodal failure.
  
  
  RESULTS
  Median follow-up was 17.6 months (range, 0-84 months). Median tumor size, positron emission tomography maximum standardized uptake value, and dose/fractionation were 2.2 cm (range, 0.8-7.2 cm), 6.7 (range, 1-59), and 50 Gray (Gy)/five fractions, respectively. Of the 342 lesions evaluated, 14.6% (50 of 342) experienced nodal failure. Nodal failure rates were 17.45% (26 of 149), 10.3% (11 of 107), 14.1% (10 of 71), and 20% (3 of 15) for lesions less than or equal to 2 cm, 2.1 to 3 cm, 3.1 to 5 cm, and greater than 5 cm, respectively. Rates of nodal failure were not significantly different between the four different size groups (p = 0.15). On univariate analysis, 2.1 to 3 cm lesions versus less than or equal to 2 cm exhibited less nodal failure after SBRT (hazard ratio = 0.406; 95% confidence interval = 0.189-0.87; p = 0.0205). No other patient, tumor, or treatment factor significantly affected nodal failure.
  
  
  CONCLUSIONS
  For early-stage NSCLC treated with SBRT, tumor size does not influence the rates of regional nodal failure. This finding warrants further investigation on the possible mechanisms of SBRT by which loco-regional control is improved.
authors.affiliation: Department of Radiation Oncology, Taussig Cancer Institute, Cleveland Clinic Foundation, Cleveland, OH.
authors.forename: Gaurav
authors.initials: G
authors.lastname: Marwaha
authors.forename: Kevin L
authors.initials: KL
authors.lastname: Stephans
authors.forename: Neil M
authors.initials: NM
authors.lastname: Woody
authors.forename: Chandana A
authors.initials: CA
authors.lastname: Reddy
authors.forename: Gregory M M
authors.initials: GM
authors.lastname: Videtic
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002289:Carcinoma, Non-Small-Cell Lung / Q000473:pathology / Q000601:surgery*; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000473:pathology / Q000601:surgery*; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D016634:Radiosurgery / Q000379:methods*; D011879:Radiotherapy Dosage; D012189:Retrospective Studies; D016896:Treatment Outcome; D047368:Tumor Burden