Biopsy and Margins Optimize Outcomes after Thermal Ablation of Colorectal Liver Metastases
Nikiforos Vasiniotis Kamarinos, Efsevia Vakiani, Mithat Gönen, Nancy E. Kemeny, Carlie Sigel, Leonard B. Saltz, Karen T. Brown, Anne M. Covey, Joseph P. Erinjeri, Lynn A. Brody, Etay Ziv, Hooman Yarmohammadi, Henry Kunin, Afşar Barlas, Elena N. Petre, T. Peter Kingham, Michael I. D’Angelica, Katia Manova‐Todorova, Stephen B. Solomon, Constantinos T. Sofocleous
Abstract
Background: Thermal ablation is a definitive local treatment for selected colorectal liver metastases (CLM) that can be ablated with adequate margins. A critical limitation has been local tumor progression (LTP). Methods: This prospective, single-group, phase 2 study enrolled patients with CLM < 5 cm in maximum diameter, at a tertiary cancer center between November 2009 and February 2019. Biopsy of the ablation zone center and margin was performed immediately after ablation. Viable tumor in tissue biopsy and ablation margins < 5 mm were assessed as predictors of 12-month LTP. Results: We enrolled 107 patients with 182 CLMs. Mean tumor size was 2.0 (range, 0.6–4.6) cm. Microwave ablation was used in 51% and radiofrequency ablation in 49% of tumors. The 12- and 24-month cumulative incidence of LTP was 22% (95% confidence interval [CI]: 17, 29) and 29% (95% CI: 23, 36), respectively. LTP at 12 months was 7% (95% CI: 3, 14) for the biopsy tumor-negative ablation zone with margins ≥ 5 mm vs. 63% (95% CI: 35, 85) for the biopsy-positive ablation zone with margins < 5 mm (p < 0.001). Conclusions: Biopsy-proven complete tumor ablation with margins of at least 5 mm achieves optimal local tumor control for CLM, regardless of the ablation modality used.