Radiofrequency ablation of hepatocellular carcinoma: correlation between local tumor progression after ablation and ablative margin.
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.
Nakazawa
Takahide
T
Gastroenterology Division of Internal Medicine, Kitasato University East Hospital, 2-1-1 Asamizodai, Sagamihara, Kanagawa 228-8520, Japan. tnakazaw@kitasato-u.ac.jp
Kokubu
Shigehiro
S
Shibuya
Akitaka
A
Ono
Koji
K
Watanabe
Masaaki
M
Hidaka
Hisashi
H
Tsuchihashi
Takeshi
T
Saigenji
Katsunori
K
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