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Purpose: To identify and compare predictors of local tumor progression (LTP)-free survival (LTPFS) after radiofrequency (RF) ablation and microwave (MW) ablation of colorectal liver metastases (CLMs).
Materials and Methods: This is a retrospective review of CLMs ablated from November 2009 to April 2015 (110 patients). Margins were measured on contrast-enhanced computed tomography (CT) 6 weeks after ablation. Clinical and technical predictors of LTPFS were assessed using a competing risk model adjusted for clustering.
Results: Technique effectiveness (complete ablation) was 93% (79/85) for RF ablation and 97% (58/60) for MW ablation (P 1⁄4 .47). The median follow-up period was significantly longer for RF ablation than for MW ablation (56 months vs. 29 months) (P < .001). There was no difference in the local tumor progression (LTP) rates between RF ablation and MW ablation (P 1⁄4 0.84). Significant predictors of shorter LTPFS for RF ablation on univariate analysis were ablation margins 5 mm or smaller (P < .001) (hazard ratio [HR]: 14.6; 95% confidence interval [CI]: 5.2–40.9) and perivascular tumors (P 1⁄4 .021) (HR: 2.2; 95% CI: 1.1–4.3); both retained significance on multivariate analysis. Significant predictors of shorter LTPFS on univariate analysis for MW ablation were ablation margins 5 mm or smaller (P < .001) (subhazard ratio: 11.6; 95% CI: 3.1–42.7) and no history of prior liver resection (P < .013) (HR: 3.2; 95%: 1.3–7.8); both retained significance on multivariate analysis. There was no LTP for tumors ablated with margins over 10 mm (median LTPFS: not reached). Perivascular tumors were not predictive for MW ablation (P 1⁄4 .43).
Conclusions: Regardless of the thermal ablation modality used, margins larger than 5 mm are critical for local tumor control, with no LTP noted for margins over 10 mm. Unlike RF ablation, the efficiency of MW ablation was not affected for perivascular tumors.
RA – 2017 Procedures Abdominal Section 0.50
RA – 2018 Procedures Abdominal Section 0.50
VI – 2016 Procedures Abdominal Angiography and Intervention, GU and GI Nonvascular Procedures 1.00
VI – 2017 Procedures Nonvascular Procedures 1.00