title: Histopathologic and immunohistochemical features of tissue adherent to multitined electrodes after RF ablation of liver malignancies can help predict local tumor progression: initial results.
abstract: OBJECTIVE
  To determine whether histopathologic and immunohistochemical features of tissue adherent to electrodes after radiofrequency (RF) ablation of liver malignancies can help predict local tumor progression (LTP).
  
  
  METHODS
  Institutional review board waiver and informed consent were obtained. Histologic and immunohistochemical examinations of tissue adherent to electrodes after RF ablation of liver malignancies were performed, with application of proliferation (Ki-67) and apoptosis (caspase-3) markers. Clinical and technical information were prospectively collected for an HIPAA-registered database. Medical records and imaging were reviewed to determine LTP for treated tumors smaller than 5 cm in diameter. LTP-free and survival rates were assessed with Kaplan-Meier method; differences between groups assessed with permutation log-rank test. Multivariate analysis assessed with Cox regression for factors related to LTP.
  
  
  RESULTS
  Sixty-eight malignant tumors treated with RF ablation were identified. Fifty-five tissue specimens were classified as coagulation necrosis (CN), thermal artifact only, or tumor cells positive for caspase-3/negative for Ki-67; and 13 as viable tumor cells (Ki-67 positive). Mean tumor size was larger in viable (3.4 cm) than in CN (2.5 cm) group before treatment (P = .01). For viable and CN groups, LTP occurred in 12 (92%) of 13 and 16 (29%) of 55 specimens, respectively; 1-year LTP-free rates were 0% and 74%, respectively (P < .001). Multivariate analysis confirmed that viable cells comprise independent risk factor for LTP (P < .001). The odds of LTP is six times greater in viable group compared with CN group for tumors 3-5 cm (hazard ratio: 5.9, 95% confidence interval: 2.4, 14.5) and 10 times greater for tumors smaller than 3 cm (hazard ratio: 10.1, 95% confidence interval: 1.7, 57.5). Median survival was 32.7 months.
  
  
  CONCLUSIONS
  Evidence of Ki-67-positive tumor cells on the electrode after hepatic RF ablation is an independent predictor of LTP.
authors.affiliation: Section of Interventional Radiology, Memorial Sloan-Kettering Cancer Center, 1275 York Ave, Room H-118, New York, NY 10065, USA. sofoclec@mskcc.org
authors.forename: Constantinos T
authors.initials: CT
authors.lastname: Sofocleous
authors.forename: Rodrigo G
authors.initials: RG
authors.lastname: Nascimento
authors.forename: Lydia M
authors.initials: LM
authors.lastname: Petrovic
authors.forename: David S
authors.initials: DS
authors.lastname: Klimstra
authors.forename: Mithat
authors.initials: M
authors.lastname: Gonen
authors.forename: Karen T
authors.initials: KT
authors.lastname: Brown
authors.forename: Lynn A
authors.initials: LA
authors.lastname: Brody
authors.forename: Anne M
authors.initials: AM
authors.lastname: Covey
authors.forename: Raymond H
authors.initials: RH
authors.lastname: Thornton
authors.forename: Yuman
authors.initials: Y
authors.lastname: Fong
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Solomon
authors.forename: Lawrence H
authors.initials: LH
authors.lastname: Schwartz
authors.forename: Ronald P
authors.initials: RP
authors.lastname: DeMatteo
authors.forename: George I
authors.initials: GI
authors.lastname: Getrajdman
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017209:Apoptosis; D017115:Catheter Ablation / Q000295:instrumentation*; D002455:Cell Division; D018450:Disease Progression; D004566:Electrodes; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D019394:Ki-67 Antigen / Q000032:analysis; D008113:Liver Neoplasms / Q000401:mortality / Q000473:pathology* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies
chemical_list: D019394:Ki-67 Antigen