title: Predictive factors for complete renal tumor ablation using RFA.
abstract: BACKGROUND
  Radiofrequency ablation (RFA) can be used to treat renal masses in patients where surgery is preferably avoided. As tumor size and location can affect ablation results, procedural planning needs to identify these factors to limit treatment to a single session and increase ablation success.
  
  
  OBJECTIVE
  To identify factors that may affect the primary efficacy of complete renal tumor ablation with radiofrequency after a single session.
  
  
  METHODS
  Percutaneous RFA (using an impedance based system) was performed using computed tomography (CT) guidance. Fifty-two renal tumors (in 44 patients) were retrospectively studied (median follow-up, 7 months). Data collection included patient demographics, tumor data (modified Renal Nephrometry Score, histopathological diagnosis), RFA treatment data (electrode placement), and follow-up results (tumor relapse). Data were analyzed through generalized estimating equations.
  
  
  RESULTS
  Primary efficacy rate was 83%. Predictors for complete ablation were optimal electrode placement (P = 0.002, OR = 16.67) and increasing distance to the collecting system (P = 0.02, OR = 1.18). Tumor size was not a predictor for complete ablation (median size, 24 mm; P = 0.069, OR = 0.47), but all tumors ≤2 cm were completely ablated. All papillary tumors and oncocytomas were completely ablated in a single session; the most common incompletely ablated tumor type was clear cell carcinoma (6 of 9).
  
  
  CONCLUSIONS
  Optimal electrode placement and a long distance from the collecting system are associated with an increased primary efficacy of renal tumor RFA. These variables need to be considered to increase primary ablation success. Further studies are needed to evaluate the effect of RFA on histopathologically different renal tumors.
authors.affiliation: Department of Radiology, University Hospital, Uppsala, Sweden vanessa.acosta-ruiz@radiol.uu.se.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Acosta Ruiz
authors.affiliation: Department of Radiology, University Hospital, Uppsala, Sweden.
authors.forename: Maria
authors.initials: M
authors.lastname: Lönnemark
authors.affiliation: Department of Urology, University Hospital, Uppsala, Sweden.
authors.forename: Einar
authors.initials: E
authors.lastname: Brekkan
authors.affiliation: Department of Radiology, University Hospital, Uppsala, Sweden.
authors.forename: Pär
authors.initials: P
authors.lastname: Dahlman
authors.affiliation: Department of Medical Sciences, Molecular Epidemiology, University Hospital, Uppsala, Sweden.
authors.forename: Lisa
authors.initials: L
authors.lastname: Wernroth
authors.affiliation: Department of Radiology, University Hospital, Uppsala, Sweden.
authors.forename: Anders
authors.initials: A
authors.lastname: Magnusson
mesh_terms: D000328:Adult; D000368:Aged; D017115:Catheter Ablation / Q000379:methods*; D003287:Contrast Media; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011846:Radio Waves; D015641:Radiography, Interventional; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
chemical_list: D003287:Contrast Media
keywords: Radiofrequency ablation (RFA); ablation; ablation success; complete ablation; predict; radiofrequency; renal tumor