Minimally invasive local therapies for liver cancer

Abstract

Primary and metastatic liver tumors are an increasing global health problem, with hepatocellular carcinoma (HCC) now being the third leading cause of cancer-related mortality worldwide. Systemic treatment options for HCC remain limited, with Sorafenib as the only prospectively validated agent shown to increase overall survival. Surgical resection and/or transplantation, locally ablative therapies and regional or locoregional therapies have filled the gap in liver tumor treatments, providing improved survival outcomes for both primary and metastatic tumors. Minimally invasive local therapies have an increasing role in the treatment of both primary and metastatic liver tumors. For patients with low volume disease, these therapies have now been established into consensus practice guidelines. This review highlights technical aspects and outcomes of commonly utilized, minimally invasive local therapies including laparoscopic liver resection (LLR), radiofrequency ablation (RFA), microwave ablation (MWA), high-intensity focused ultrasound (HIFU), irreversible electroporation (IRE), and stereotactic body radiation therapy (SBRT). In addition, the role of combination treatment strategies utilizing these minimally invasive techniques is reviewed.

Keywords: Liver; hepatocellular carcinoma (HCC); metastasis.

Figure 1

Barcelona clinic liver cancer treatment strategy. (Reprinted with permission from Forner et al.²).

Figure 2

Hong Kong Liver Cancer prognostic classification and treatment strategy. (Reprinted with permission from Yau et al.²⁶). Early tumor: ≤5 cm, ≤3 tumor nodules, and no intrahepatic venous invasion; Intermediate tumor: (1) ≤5 cm, either >3 tumor nodules or with intrahepatic venous invasion, or (2) >5 cm, ≤3 tumor nodules and no intrahepatic venous invasion; and Locally advanced tumor: (1) ≤5 cm, > 3 tumor nodules with intrahepatic venous invasion, or (2) >5 cm, >3 tumor nodules or/and with intrahepatic venous invasion, or (3) diffuse tumor. EVM, extrahepatic vascular invasion/metastasis; LT, liver transplantation.

Figure 3

A 64-year-old female s/p right hemicolectomy for adenocarcinoma presenting with solitary segment 6 metastases discovered 3 years post-operatively on routine surveillance imaging. (A,B) Axial contrast enhanced CT image and corresponding PET image demonstrating FDG-avid segment 6 liver metastasis (arrow); (C) post-operative axial CT image obtained 8 years after laparoscopic liver resection demonstrating no residual or recurrent disease.

Figure 4

A 56-year-old male with hepatitis C complicated by hepatocellular carcinoma, not a surgical candidate, presenting with an isolated tumor in segment 6 of the liver. (A) T2 weighted axial MRI image demonstrates lesion in segment 6 (arrow). (B) Non-contrast axial CT image during procedure with applicator in the hypoattenuating mass. Immediate contrast-enhanced post-RFA axial CT images in arterial (C) and portal venous (D) phases show complete ablation in the area of the tumor. (E) T2 weighted axial MRI image at two year follow-up demonstrates complete necrosis of the segment 6 tumor. RFA, radiofrequency ablation.

Figure 5

A 40-year-old female with metastatic breast carcinoma who presents with a focal metastatic tumor to segment 7 of the liver. (A) Axial post-contrast MRI image demonstrates 1.7×1.1 cm² hypointense mass in segment 7 (arrow). Intraprocedural ultrasound images (B) During needle placement (arrow), (C) During ablation. Note the hyperechoic area which represents microbubble formation during heating (arrow). (D) Non-contrast axial CT image during procedure demonstrates applicator in place. (E) Non-contrast axial CT image immediately after ablation shows a hypodense region with focal air bubbles indicative of the ablation zone. (F) Fused axial PET-CT image 3 months post-ablation demonstrating ablation cavity with no evidence of residual FDG-avidity (arrow).

Figure 6

A 61-year-old male with history of localized rectal cancer treated with chemoradiation and surgery; subsequently diagnosed 2 years later with isolated liver lesion growing in size and avidity, biopsied positive for metastatic rectal cancer. Patient initially refused all invasive procedures including surgery, opting for chemotherapy alone, then ultimately agreed to SBRT. (A) Pretreatment axial fused PET-CT image demonstrating metastatic segment 7 liver lesion with SUV 3.8 (arrow). (B) Treatment plan depicting prescription isodose line (in red) with rapid dose fall off around the tumor. (C) Axial fused PET-CT obtained 18 months after SBRT demonstrating no evidence of disease. (D) Axial contrast enhanced CT image obtained 4 years after SBRT demonstrating no evidence of disease. SBRT, stereotactic body radiation therapy.