Effectiveness and Safety of the Simultaneous Radiotherapy and Hyperthermia After Transarterial Chemoembolization in Hepatocellular Carcinoma Patients Combined With Portal Vein Tumor Thrombosis

1.1 Hepatocellular carcinoma (HCC) and standard treatment HCC is the third most common cause of cancer death globally. It is also the second cause of cancer mortality in Korea, despite the incidence of HCC was fifth. The most important cause of this discrepancy is connected with the fact that the significant portion of the HCC is detected as unresectable status. At the point of HCC diagnosis, only 30% of the patients could receive standard curative treatment, like resection, liver transplantation, and radiofrequency ablation (RFA), TACE has been shown in randomized trials to improve survival compared with symptomatic therapy alone, in the patients without macrovascular involvement, extrahepatic disease and tumor related symptoms. However, in the recent review of TACE, TACE might be contraindicate or not recommended in the patients who showed vascular tumor invasion, more than 10 cm size, poor portal blood flow and/or repeated poor response.

1.2 HCC with PVTT The presence of PVTT in patients with HCC is one of the most significant prognostic factors for poor prognosis, without treatment, their survival is less than 3 months. Recently, Sorafenib, which is one of the target agents, showed survival advantage on unresectable HCC patients in two randomized study. In those study, sorafenib improved approximately three month overall survival increment, however, the median survival duration was only 10.7 months in experiment group (received sorafenib), and even 6.5 months in Asian-Pacific trial. Additionally, the possibility that sorafenib effect could be reduced in the patients had hepatitis B virus (HBV) was suggested in the subgroup analysis.

1.3 Radiation therapy (RT) for the HCC The use of RT in HCC is increased with the radiation technological advances. In the unresectable patients, RT showed 50 to 60% response rate with the dose response relationship. Especially, in the HCC patients who combined with PVTT, RT showed 50% of local control and about 10 months survival duration. Despite the standard treatment of the HCC combined with PVTT is sorafenib, but Korean Liver Cancer Study Group (KLCSG) recommend RT as an option in those patients.

Investigators previously reported the retrospective study that the scheduled interval TACE followed by RT for HCC combined with PVTT and 60% of the patients showed objective response without significant elevation of complication.

1.4 Hyperthermia It is reported that hyperthermia is effective in S phase, Low partial oxygen pressure (pO2), acidic condition, and low perfusion site which are known as radio-resistant. Because of these characteristics, it considered as the most valuable radiosensitizer in cancer treatment, theoretically. Furthermore ,mild hyperthermia (41 to 41.5 ºC) can promote tumor reoxygenation.

1.5 Purpose of the study Based on those studies, we start this prospective study to evaluate the objective response and adverse event in the combination treatment of RT and hyperthermia after TACE in the unresectable HCC patients who combined with PVTT.

2. Hypothesis and sample size Several prospective trials showed 50% to 60% of objective response rate when conventional RT was administered for HCC with PVTT, thus we determined the objective response rate of conventional RT as 60%. We expect additional 20% increase of the local progression free rate than conventional RT when treated with combined RT and hyperthermia for HCC with PVTT.

To determine sample size, we designed to have 80% power to detect an absolute difference of 20% points in objective response rate between combined RT and hyperthermia and conventional RT, with a two-sided alpha level of 0.05. A total of 87 patients are required for this study considering a drop-out rate of 10%.