Percutaneous local ablation therapy in small hepatocellular carcinoma.

Periodic screening programs conducted in various countries, applying sonography and serum alfa-fetoprotein to patients with chronic liver disease, have identified numerous small hepatocellular carcinoma (HCC). Although surgical resection is generally preferred for curative ablation, the long-term survival rates following resection are no better than those following local ablation. Current local ablation modalities are typically easily performed, safe and repeatable procedures, and include percutaneous ethanol injection (PEI), percutaneous acetic acid injection (PAI), radiofrequency ablation (RFA) and microwave coagulation therapy (MCT). The mechanisms of PEI or PAI are based on the dehydration, intracellular protein damage, and thrombo-ischemic effects of absolute ethanol or acetic acid on the tumor cells. Meanwhile, the mechanisms of RFA or MCT are based on the generation of friction heat between the tissue and electric current or microwave emitted by an RF or microwave electrode into the tumor. The heat causes coagulation, followed by cellular death as soon as the temperature in the target area exceeds 60 degrees C. From previous comparative studies of these procedures, RFA may be superior to PEI, PAI or MCT owing to its larger ablation volume, fewer treatment sessions and more predictable ablation size. The rate of complete necrosis of the target tumors was approximately 90-98% by RFA, 80-95% by PEI, 90-95% by PAI and 94% by MCT. Moreover, the survival rates of these four modalities were approximately 90% at 1 year, 70% at 3 years, and 40-50% at 5 years. In tentative conclusion, RFA is the preferred local ablation therapy for most small HCC. However, PEI is a useful alternative where RFA is unavailable.