The Role of Thermal Ablation for Colorectal Liver Metastases in the Era of Effective Chemotherapy

After the introduction of new chemotherapeutic agents, including oxaliplatin and irinotecan, chemotherapy can induce tumor down-staging in patients with initially unresectable colorectal liver metastases (CRLM), which thus allows for hepatic resection. Recently, the application of thermal ablation, especially radiofrequency ablation (RFA), has been extended from hepatocellular carcinoma (HCC) to CRLM. However, randomized trials show little evidence to support the clinical efficacy of RFA for CRLM. We herein evaluate the clinical efficacy and the role of thermal ablation for CRLM in this era of effective chemotherapy. Non-randomized retrospective studies have demonstrated the effects of RFA alone for CRLM without new chemotherapeutic agents. The three- and five-year survival rates of RFA alone for CRLM ranged from 42% to 57%, and 21% to 37%, respectively. The local recurrence rate was between 9% and 15%. In contrast, the five-year survival rates after RFA with perioperative chemotherapy of irinotecan- or oxaliplatin-based regimens ranged from 34% to 54%. The local recurrence at the site of RFA ranged from 29.7% to 42.5%. After the introduction of new chemotherapeutic agents, RFA with perioperative chemotherapy of irinotecan- or oxaliplatin-based regimens may improve the survival in patients with CRLM compared to RFA alone. However, the rate of local recurrence of RFA with perioperative chemotherapy was similar to that after RFA alone. The three- and five-year survival rates of RFA in combination with hepatic resection for CRLM ranged from 38% to 47%, and 47% to 68%, respectively. The rate of local recurrence at the site of RFA was between 5 and 17.4%, respectively. In our study, hepatic resection combined with RFA after the FOLFOX regimen resulted in excellent local control rates (2.5% recurrence per tumor). In this era of new and more effective chemotherapy, combining RFA with chemotherapy or hepatic resection for CRLM can extend the indications of surgical resection and further improve patient survival.