Factors influencing complete tumor destruction, local tumor progression and survival after radiofrequency ablation of metastatic liver tumors

Abstract

Aim: To research on the factors influencing complete tumor destruction (CD), local tumor progression (LTP), and survival after US-guided percutaneous radiofrequency ablation (RFA) in patients with liver metastases. Patients and methods: 133 patients with 276 metastases were treated using monopolar RFA with perfused applicators, 36 patients with 65 metastases were treated with multipolar RFA using 3 bipolar applicators, and 8 patients with 11 metastases were treated with expandable multitined perfused RFA, in a 6-year period. The origin was colorectal cancer (211 lesions), breast cancer (45 lesions), esophageal, gastric, pancreatic, gallbladder, renal, urinary bladder, uterine and ovarian cancer, neuroendocrine tumors and sarcomas (96 lesions). The mean tumor size was 3.38+/-1.82cm (0.5–11.5) and was larger in the multipolar and expandable RFA groups. The achieved destruction was assessed with contrast-enhanced CT, CEUS and fine-needle aspiration biopsy. Patients were followed up for 1–47 months with US and CT. The influencing factors were studied with binary logistic and Cox-regression analysis, Kaplan-Meier method, Log Rank, Breslow and Tarone-Ware tests. Results: CD was achieved in 70.7% of the lesions after monopolar RFA, in 71.4% after multipolar RFA, and in 10/11 lesions after expandable RFA, significantly depending on the size, applied amount of RF energy per tumor volume and location of the lesion, but not on the tumor origin. LTP rate per lesion was 31.5% after monopolar and 18.2% after multipolar RFA, depending on the size and applied amount of RF energy. The achievement of CD of all lesions per patient depended on the size of the largest lesion and number of lesions (p<0.001). The probability of LTP and time to LTP per patient depended on the size of the largest lesion, number of lesions and subsequent chemotherapy (p<0.001). Median survival was 42 months (95% CI 38.64–45.43). Cumulative 36-month survival, estimated from Kaplan-Meier curve, was 91.4%. Factors significantly influencing survival were the size of the largest lesion, achievement of CD of all lesions and additional chemotherapy. Conclusion: Multipolar and expandable perfused RFA are preferable in medium-sized and large lesions, while monopolar RFA is suitable for risky and difficult to approach locations. Complete ablation of all lesions and multidisciplinary approach to the patients with liver metastases lengthens survival.