Minimally Invasive Therapies for Hepatocellular Cancer: Ablation Therapies

Abstract

Ablation therapy is proving to be a major tool in the anti-cancer armamentarium. The superb diagnostic capabilities of CT, US, and MRI, along with IR techniques, have combined to allow percutaneous tumor ablation to become fairly widespread in availability at major centers. The fundamental concept of ablation is that the extremes of temperature kill cancer. Thus both heating and freezing methods are effectively tumoricidal. Heating options are via radiofrequency, laser, and microwave. The former is utilized most frequently, laser least, and microwave is in its early clinical experience. Other primary methods of percutaneous tumor ablation include cryotherapy (CRYO) and direct chemical injection. While various agents have been injected for direct percutaneous injection into tumors, alcohol ablation is most effective, and has been utilized most frequently. The efficacy of radiofrequency ablation (RFA) is related to the size of the liver tumor. It is accepted that the lesion should not exceed 2.5–3.0 cm to obtain complete necrosis. It has been reported that certain microwave ablation (MWA) devices may allow successful treatment of lesions as large as 5 cm with an acceptable margin of safety. Notwithstanding, RFA commonly is utilized for lesions greater than 3 cm in diameter, occasionally for palliative debulking rather than cure. Guidelines may assist in the selection and use of the more widely used thermal technologies to provide optimal Predictive, Preventive and Personalized Medicine (PPPM). To achieve maximal effectiveness for cure, basic treatment precepts must be understood and adhered to, including: (1) proper patient selection; (2) treatment of the entire lesion; (3) providing adequate tumor margins.