Histopathologic and immunohistochemical features of tissue adherent to multitined electrodes after RF ablation of liver malignancies can help predict local tumor progression: initial results.
OBJECTIVE
To determine whether histopathologic and immunohistochemical features of tissue adherent to electrodes after radiofrequency (RF) ablation of liver malignancies can help predict local tumor progression (LTP).


METHODS
Institutional review board waiver and informed consent were obtained. Histologic and immunohistochemical examinations of tissue adherent to electrodes after RF ablation of liver malignancies were performed, with application of proliferation (Ki-67) and apoptosis (caspase-3) markers. Clinical and technical information were prospectively collected for an HIPAA-registered database. Medical records and imaging were reviewed to determine LTP for treated tumors smaller than 5 cm in diameter. LTP-free and survival rates were assessed with Kaplan-Meier method; differences between groups assessed with permutation log-rank test. Multivariate analysis assessed with Cox regression for factors related to LTP.


RESULTS
Sixty-eight malignant tumors treated with RF ablation were identified. Fifty-five tissue specimens were classified as coagulation necrosis (CN), thermal artifact only, or tumor cells positive for caspase-3/negative for Ki-67; and 13 as viable tumor cells (Ki-67 positive). Mean tumor size was larger in viable (3.4 cm) than in CN (2.5 cm) group before treatment (P = .01). For viable and CN groups, LTP occurred in 12 (92%) of 13 and 16 (29%) of 55 specimens, respectively; 1-year LTP-free rates were 0% and 74%, respectively (P < .001). Multivariate analysis confirmed that viable cells comprise independent risk factor for LTP (P < .001). The odds of LTP is six times greater in viable group compared with CN group for tumors 3-5 cm (hazard ratio: 5.9, 95% confidence interval: 2.4, 14.5) and 10 times greater for tumors smaller than 3 cm (hazard ratio: 10.1, 95% confidence interval: 1.7, 57.5). Median survival was 32.7 months.


CONCLUSIONS
Evidence of Ki-67-positive tumor cells on the electrode after hepatic RF ablation is an independent predictor of LTP.
Sofocleous
Constantinos T
CT
Section of Interventional Radiology, Memorial Sloan-Kettering Cancer Center, 1275 York Ave, Room H-118, New York, NY 10065, USA. sofoclec@mskcc.org
Nascimento
Rodrigo G
RG
Petrovic
Lydia M
LM
Klimstra
David S
DS
Gonen
Mithat
M
Brown
Karen T
KT
Brody
Lynn A
LA
Covey
Anne M
AM
Thornton
Raymond H
RH
Fong
Yuman
Y
Solomon
Stephen B
SB
Schwartz
Lawrence H
LH
DeMatteo
Ronald P
RP
Getrajdman
George I
GI
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017209:Apoptosis; D017115:Catheter Ablation / Q000295:instrumentation*; D002455:Cell Division; D018450:Disease Progression; D004566:Electrodes; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D019394:Ki-67 Antigen / Q000032:analysis; D008113:Liver Neoplasms / Q000401:mortality / Q000473:pathology* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies
D019394:Ki-67 Antigen