Study on the effect of chemoembolization combined with microwave ablation for the treatment of hepatocellular carcinoma in rats

Abstract

H epatocellular carcinoma (HCC) is the fifth most common malignancy among men, and the seventh most common malignancy among women. Although morbidity and mortality are very high, no standardized treatment algorithm exists to date (1). Transarterial chemoembolization (TACE) is a frequently used interventional treatment for patients with inoperable HCC (2). Direct application of drugs into tumor feeding branches, allows for higher local chemotherapeutic concentrations with less systemic side effects. However, TACE has not been shown to notably prolong the overall survival rate, mainly due to local and distal tumor recurrence after treatment (3). Microwave ablation is a minimally invasive technique with low complication rate for the nonsurgical treatment of HCC (4). Electromagnetic waves at frequencies of 900-2450 MHz are used to induce coagulation necrosis. Polar molecules (mainly water dipoles) try to realign themselves with the direction of current in an electromagnetic field. The oscillation produced by constant realignment causes friction and a heating effect. However, it has been shown that local tumor control is highly dependent on complete tumor ablation, and recurrence in larger nodules (> 5 cm in diameter) is remarkably worse than in smaller ones (5, 6).Recently published studies imply that a combination of TACE and local ablation might have a synergistic effect on HCC (7). TACE leads to inflammatory edema, therefore increasing the watery content of the tumor, which the technique of microwave ablation uses to produce heat (8). Furthermore, central tumor parts in close vicinity to the probe receive the greatest thermal insult during physical ablation, while TACE works best on the better vascularized peripheral tumor areas (3). Trials with over 100 patients demonstrated that combined therapy of microwave ablation applied within six weeks after TACE can effective- 150From the Institute for Diagnostic and Interventional Radiology (T.J.V.  t.vogl@em.uni-frankfurt.de, A.T.,