title: Radiofrequency ablation of hepatocellular carcinoma: correlation between local tumor progression after ablation and ablative margin.
abstract: OBJECTIVE
  To identify the determinants of tumor progression, we examined the ablation zones and patterns of local progression of small single primary hepatocellular carcinomas after radiofrequency ablation.
  
  
  METHODS
  Eighty-five patients with single primary hepatocellular carcinoma less than 3 cm in diameter underwent complete tumor ablation. Clinical and biochemical features, tumor characteristics, tumor location within 5 mm from intrahepatic vessels, needle biopsy before treatment, and presence of ablative margin of 5 mm or more were statistically analyzed as determinants of local tumor progression. The Kaplan-Meier method and a Cox model were used for the analyses. Patterns of local tumor progression were examined by image analysis.
  
  
  RESULTS
  During a median observation period of 30.3 months, 14 (16.5%) of the 85 patients had local tumor progression. The results of the log-rank test showed that the presence of vessels contiguous with the tumor (p = 0.0292) and the absence of an ablative margin of at least 5 mm (p = 0.019) significantly correlated with local tumor progression. Cox regression analysis showed that the absence of an ablative margin of at least 5 mm was an independent factor (p = 0.04). The most common pattern of local tumor progression was a single viable outgrowth from the side of the ablated area when the ablative margin was less than 5 mm. Multiple viable outgrowths were observed in one case despite the presence of an ablative margin greater than 5 mm.
  
  
  CONCLUSIONS
  An ablation zone with an ablative margin of 5 mm or greater was the most important factor for local control of hepatocellular carcinoma.
authors.affiliation: Gastroenterology Division of Internal Medicine, Kitasato University East Hospital, 2-1-1 Asamizodai, Sagamihara, Kanagawa 228-8520, Japan. tnakazaw@kitasato-u.ac.jp
authors.forename: Takahide
authors.initials: T
authors.lastname: Nakazawa
authors.forename: Shigehiro
authors.initials: S
authors.lastname: Kokubu
authors.forename: Akitaka
authors.initials: A
authors.lastname: Shibuya
authors.forename: Koji
authors.initials: K
authors.lastname: Ono
authors.forename: Masaaki
authors.initials: M
authors.lastname: Watanabe
authors.forename: Hisashi
authors.initials: H
authors.lastname: Hidaka
authors.forename: Takeshi
authors.initials: T
authors.lastname: Tsuchihashi
authors.forename: Katsunori
authors.initials: K
authors.lastname: Saigenji
mesh_terms: D006528:Carcinoma, Hepatocellular / Q000175:diagnosis / Q000453:epidemiology* / Q000601:surgery*; D017115:Catheter Ablation / Q000706:statistics & numerical data*; D018572:Disease-Free Survival; D005260:Female; D006498:Hepatectomy / Q000706:statistics & numerical data; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008113:Liver Neoplasms / Q000175:diagnosis / Q000453:epidemiology* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis / Q000453:epidemiology* / Q000517:prevention & control*; D015995:Prevalence; D015203:Reproducibility of Results; D018570:Risk Assessment / Q000379:methods; D012307:Risk Factors; D012680:Sensitivity and Specificity; D016896:Treatment Outcome