Percutaneous thermal ablation of subcapsular hepatocellular carcinomas: influence of tumor-surface contact and protrusion on therapeutic efficacy and safety.
PURPOSE
To evaluate therapeutic efficacy and complication of percutaneous thermal ablation of subcapsular hepatocellular carcinomas (HCCs), and how these may be influenced by the degree of tumor to liver surface contact and tumor protrusion from liver surface.


MATERIALS AND METHODS
Our retrospective study was approved by the Institutional Review Board. Between January 2006 and December 2013, 290 patients (82 women, 208 men; mean age, 64.5 years; range, 33-89 years) with 474 subcapsular (within 1 cm to the liver surface) HCCs (mean size, 23.7 mm; range, 6-71 mm) underwent percutaneous thermal ablation. The HCCs were divided into surface contact group (n = 243) and non-surface contact group (n = 231). The former was further subdivided into exophytic and non-exophytic HCCs. Technical success, primary technique efficacy, local tumor progression (LTP), and secondary technique efficacy rates were analyzed and compared by the chi-square test or Fisher exact test. Prognostic factors for LTP and secondary technique efficacy were assessed using the Cox regression model. Major complications were also assessed.


RESULTS
With median follow-up of 15 months (range, 1-87 months), technical success and primary technique efficacy were 98.7% and 95.7% % in the non-surface contact group; 96.4% and 94.0% in the non-exophytic group; and 100% and 94.7% in the exophytic group (p > 0.05). Tumor size > 3 cm was a significant predictor for LTP, but not for secondary efficacy. Overall major complication rate was 3.8% (24/624) and was not different among the three groups.


CONCLUSION
Subcapsular HCCs can be effectively treated with thermal ablation techniques. Degree of tumor-surface contact including moderate protrusion does not appear to limit feasibility or procedure effectiveness.


KEY POINTS
• Subcapsular HCCs can be effectively treated with thermal therapy when proper image-guided technique and assistive techniques are applied. • Degree of tumor surface contact including moderate protrusion does not appear to limit feasibility or procedure effectiveness. • Major complications after percutaneous thermal ablation of subcapsular HCCs such as tumor seeding can be minimized by avoiding breach of the tumor capsule exposed to the peritoneal surface and use of tract ablation.
['Worakitsitisatorn|Akeanong|A|', 'Lu|David S|DS|http://orcid.org/0000-0002-3263-4476', 'Lee|Min Woo|MW|', 'Asvadi|Nazanin H|NH|', 'Moshksar|Amin|A|', 'Yuen|Alexander D|AD|', 'McWilliams|Justin|J|', 'Raman|Steven S|SS|']
D000328:Adult D000368:Aged D000369:Aged, 80 and over D006528:Carcinoma, Hepatocellular D017115:Catheter Ablation D005260:Female D006801:Humans D006979:Hyperthermia, Induced D008113:Liver Neoplasms D008297:Male D008875:Middle Aged D009366:Neoplasm Seeding D012189:Retrospective Studies D016896:Treatment Outcome
Hepatocellular carcinoma Catheter ablation Disease progression Postoperative complications Survival analysis