Dose-response relationship in local radiotherapy for hepatocellular carcinoma

Abstract

Purpose : Dose escalation using three-dimensional conformal radiotherapy (3D-CRT) is based on the hypothesis that increasing the dose can enhance tumor control. This study aimed to determine whether a dose-response relationship exists in local radiotherapy for primary hepatocellular carcinoma (HCC). Methods and Materials : One hundred fifty-eight patients were enrolled in the present study between January 1992 and March 2000. The exclusion criteria included the presence of an extrahepatic metastasis, liver cirrhosis of Child class C, tumors occupying more than two-thirds of the entire liver, and a performance status on the Eastern Cooperative Oncology Group scale of more than 3. Radiotherapy was given to the field, including the tumor, with generous margin using 6- or 10-MV X-rays. The mean radiation dose was 48.2 ± 7.9 Gy in daily 1.8-Gy fractions. The tumor response was assessed based on diagnostic radiologic examinations, including a computed tomography scan, magnetic resonance imaging, and hepatic artery angiography 4–8 weeks after the completion of treatment. Liver toxicity and gastrointestinal complications were evaluated. Results : An objective response was observed in 106 of 158 (67.1%) patients. Statistical analysis revealed that the total dose was the most significant factor associated with the tumor response. The response rates in patients treated with doses <40 Gy, 40–50 Gy, and >50 Gy were 29.2%, 68.6%, and 77.1%, respectively. Survivals at 1 and 2 years after radiotherapy were 41.8% and 19.9%, respectively, with a median survival time of 10 months. The rate of liver toxicity according to the doses <40 Gy, 40–50 Gy, and >50 Gy was 4.2%, 5.9%, and 8.4%, respectively, and the rate of gastrointestinal complications was 4.2%, 9.9%, and 13.2%, respectively. Conclusions : The present study showed the existence of a dose-response relationship in local radiotherapy for primary HCC. Only the radiation dose was a significant factor for predicting an objective response. The results of this study showed that 3D-CRT can theoretically be used for treating primary HCC.