Conversion surgery after preoperative therapy for advanced hepatocellular carcinoma in the era of molecular targeted therapy and immune checkpoint inhibitors

Optimal strategies for advanced hepatocellular carcinoma (HCC) tumors, such as those with vascular tumor thrombus and those with extrahepatic metastases are unclear.A literature review was conducted focusing on conversion surgery for HCC after molecular targeted therapy and therapy using immune checkpoint inhibitors.Upfront surgical resection of advanced HCC tumors has been challenged at some institutions because of lack of promising therapeutic options. Preoperative transcatheter arterial chemoembolization, hepatic arterial infusion chemotherapy, and radiotherapy in patients with unresectable HCC were developed to improve long-term outcome, but the results were not promising. Nonetheless, the recent advent of molecular targeted therapies and immune check-point inhibitors, enabling frequent tumor responses, has accelerated the use of conversion surgery after these therapies in patients with initially unresectable HCC. Increasing numbers of conversion surgeries after lenvatinib therapy has been reported, and the first prospective clinical trial assessing conversion surgery after lenvatinib therapy in initially unresectable HCC has been commenced. Furthermore, the superiority of combination therapy using atezolizumab and bevacizumab over sorafenib, a conventional first-line drug for unresectable HCC, in terms of overall survival and tumor response has been demonstrated, and the use of this regimen alongside conversion surgery is expected in addition to lenvatinib.The literature demonstrated the feasibility of conversion surgery after systemic therapy. Further clinical investigation of surgery after systemic therapy for advanced HCC may be undertaken by clearly distinguishing the tumor status as technically unresectable or oncologically unresectable but technically resectable.