title: Risk factors for local recurrence of small hepatocellular carcinoma tumors after a single session, single application of percutaneous radiofrequency ablation.
abstract: BACKGROUND
  The objectives of this study were to clarify risk factors for local tumor recurrence and to determine which patients with hepatocellular carcinoma (HCC) are most suitable for a single session, single application of percutaneous radiofrequency (RF) ablation.
  
  
  METHODS
  Fifty-six consecutive patients with 65 HCC tumors measuring <or= 3 cm in greatest dimension who received a single session, single application of percutaneous RF ablation and who achieved optimal tumor ablation, as assessed by an immediate computed tomography scan, were enrolled in this study. Six possible factors for local recurrence were analyzed using a Cox proportional hazards regression model: tumor size, tumor location, proximity of the tumor to intrahepatic large vessels, types of electrodes used, prior treatment, and observation of impedance rises. Local recurrence free intervals were estimated using the Kaplan-Meier method, and differences between groups were compared using the log-rank test.
  
  
  RESULTS
  The Kaplan-Meier estimates of overall cumulative local recurrence free intervals after a single RF ablation treatment were 76% (95% confidence interval [95%CI], 70.9-81.7%) at 12 months and 74% (95%CI, 68.2-79.6%) at 15 months. The log-rank test revealed a statistically significant difference between the local recurrence free intervals according to tumor size (P = 0.001) and tumor location (P < 0.001). Further investigation with a Cox regression analysis indicated that a greatest tumor dimension > 2 cm (risk ratio [RR], 4.9; 95%CI, 1.3-16.4; P = 0.019) and subcapsular location (RR, 5.2; 95%CI, 1.7-16.6; P = 0.005) were associated independently with local recurrence. The other four factors were not associated with local recurrence in this study.
  
  
  CONCLUSIONS
  A single session, single application of RF ablation produced favorable local control. Patients who have nonsubcapsular HCC tumors measuring <or= 2 cm in greatest dimension may be the most suitable candidates for a single-session, single application of RF ablation.
authors.affiliation: Second Department of Internal Medicine, Faculty of Medicine, Kagoshima University, Kagoshima, Japan. cbi75530@pop02.odn.ne.jp
authors.forename: Yasuji
authors.initials: Y
authors.lastname: Komorizono
authors.forename: Makoto
authors.initials: M
authors.lastname: Oketani
authors.forename: Katsumi
authors.initials: K
authors.lastname: Sako
authors.forename: Naruhiro
authors.initials: N
authors.lastname: Yamasaki
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Shibatou
authors.forename: Masahiko
authors.initials: M
authors.lastname: Maeda
authors.forename: Kazunori
authors.initials: K
authors.lastname: Kohara
authors.forename: Shuhou
authors.initials: S
authors.lastname: Shigenobu
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Ishibashi
authors.forename: Terukatsu
authors.initials: T
authors.lastname: Arima
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D006528:Carcinoma, Hepatocellular / Q000601:surgery*; D017115:Catheter Ablation; D018572:Disease-Free Survival; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008113:Liver Neoplasms / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D018579:Patient Selection; D012307:Risk Factors