Three-Dimensional Margin as a Predictor of Local Tumor Progression after Microwave Ablation: Intraprocedural versus 4-8-Week Postablation Assessment.

PURPOSE: To evaluate the prognostic accuracy of intraprocedural and 4-8-week (current standard) post-microwave ablation zone (AZ) and margin assessments for prediction of local tumor progression (LTP) using 3-dimensional (3D) software. MATERIALS AND METHODS: Data regarding 100 colorectal liver metastases (CLMs) in 75 patients were collected from 2 prospective fluorodeoxyglucose positron emission tomography (PET)/computed tomography (CT)-guided microwave ablation (MWA) trials. The target CLMs and theoretical 5- and 10-mm margins were segmented and registered intraprocedurally and at 4-8 weeks after MWA contrast-enhanced CT (or magnetic resonance [MR] imaging) using the same methodology and 3D software. Tumor and 5- and 10-mm minimal margin (MM) volumes not covered by the AZ were defined as volumes of insufficient coverage (VICs). The intraprocedural and 4-8-week post-MWA VICs were compared as predictors of LTP using receiver operating characteristic curve analysis. RESULTS: The median follow-up time was 19.6 months (interquartile range, 7.97-36.5 months). VICs for 5- and 10-mm MMs were predictive of LTP at both time assessments. The highest accuracy for the prediction of LTP was documented with the intra-ablation 5-mm VIC (area under the curve [AUC], 0.78; 95% confidence interval, 0.66-0.89). LTP for a VIC of 6-10-mm margin category was 11.4% compared with 4.3% for >10-mm margin category (P < .001). CONCLUSIONS: A 3D 5-mm MM is a critical endpoint of thermal ablation, whereas optimal local tumor control is noted with a 10-mm MM. Higher AUCs for prediction of LTP were achieved for intraprocedural evaluation than for the 4-8-week postablation 3D evaluation of the AZ.

Use of Metformin and Survival in Patients with Hepatocellular Carcinoma (HCC) Undergoing Liver Directed Therapy: Analysis of a Nationwide Cancer Registry.

BACKGROUND: Examine the association of metformin use and overall survival (OS) in patients with HCC undergoing image-guided liver-directed therapy (LDT): ablation, transarterial chemoembolization (TACE), or Yttrium-90 radioembolization (Y90 RE). METHODS: Using National Cancer Institute Surveillance, Epidemiology, and End Results registry and Medicare claims databases between 2007 and 2016, we identified patients ≥ 66 years who underwent LDT within 30 days of HCC diagnosis. Patients with liver transplant, surgical resection, and other malignancies were excluded. Metformin use was identified by at least two prescription claims within 6 months before LDT. OS was measured by time between first LDT and death or last Medicare observation. Comparisons were performed between both all and diabetic patients on and not on metformin. RESULTS: Of 2746 Medicare beneficiaries with HCC undergoing LDT, 1315 (47.9%) had diabetes or diabetes-related complications. Among all and diabetic patients, 433(15.8%) and 402 (30.6%) were on metformin respectively. Median OS was greater for patients on metformin (19.6 months, 95% CI 17.1-23.0) vs those not (16.0 months, 15.0-16.9; p = 0.0238). Patients on metformin had lower risk of death undergoing ablation (HR 0.70; 0.51-0.95; p = 0.0239) and TACE (HR 0.76, 0.66-0.87; p = 0.0001), but not Y90 RE (HR1.22, 0.89-1.69; p = 0.2231). Among diabetics, OS was greater for those on metformin vs those not (HR 0.77, 0.68-0.88; p < 0.0001). Diabetic patients on metformin had longer OS undergoing TACE (HR 0.71, 0.61-0.83; p < 0.0001), but not ablation (HR 0.74, 0.52-1.04; p = 0.0886) or Y90 RE (HR 1.26, 0.87-1.85; p = 0.2217). CONCLUSION: Metformin use is associated with improved survival in HCC patients undergoing TACE and ablation.