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Ki67 as a prognostic biomarker of 5-year oncologic outcomes following ablation of liver malignancies.

e21160 Background: Ki67 has been used as a prognostic biomarker of oncologic outcomes after treatment of several malignant tumors. The current study assessed the long term predictive of Ki67 positive tumor cells on tissue adherent to multitined electrodes, on local tumor progression (LTP) and overall survival (OS) after radiofrequency ablation (RFA) of liver tumors.


METHODS
Examination of tissue adherent to electrodes after RF ablation of liver malignancies was performed looking for proliferation (Ki-67) and apoptosis (caspase-3) markers. Clinical and technical information was collected from a hepatobiliary database. In patients with tumors smaller than 5cm in diameter a retrospective review of medical records and imaging was performed. Local Tumor Progression Free Survival (LPFS) and overall survival (OS) probabilities were estimated with the Kaplan-Meier methodology and compared using the log-rank test. Multivariate analysis was performed to assess the effect of tumor size, primary pathology, and post ablation tissue characteristics on LPFS and OS.


RESULTS
Sixty-eight ablated tumors were identified in 63 patients. Post ablation tissue examinations classified 55 specimens as completely ablated/ coagulation necrosis (CN) and 13 as viable tumor (V) containing tumor cells positive for Ki-67. Mean tumor size was larger in the V (3.4 cm) than in the CN (2.5 cm) (P = .017). Ninety-two percent of patients with V and 58% with CN have died within the median follow-up of 63 months. The 1-, 3-, and 5-year LPFS and OS probabilities were significantly prolonged in the CN group (table).


CONCLUSIONS
Viable tumor cells (Ki-67+) on the electrode after RFA of hepatic tumors is an independent predictor of local tumor progression free and overall survival on multivariant analysis. [Table: see text].