Efficacy of stereotactic body radiotherapy for hepatocellular carcinoma with portal vein tumor thrombosis/inferior vena cava tumor thrombosis: evaluation by comparison with conventional three-dimensional conformal radiotherapy

Abstract

This study aimed to evaluate the efficacy of stereotactic body radiotherapy (SBRT) compared with three-dimensional conformal radiotherapy (3DCRT). Forty-three patients with portal vein tumor thrombosis (PVTT)/inferior vena cava tumor thrombosis (IVCTT) treated with SBRT (27 with CyberKnife (CK) and 16 with TrueBeam (TB)) from April 2013 to December 2014, and 54 treated with 3DCRT from June 2008 to March 2013 were evaluated. Dosimetric parameters, response to radiotherapy (RT) and survival outcomes were compared in total SBRT vs. 3DCRT, CK vs. 3DCRT and TB vs. 3DCRT, respectively. The median biologically effective dose 10 (BED₁₀) values in total SBRT, CK, TB and 3DCRT were 73.4 Gy₁₀, 75.0 Gy₁₀, 60.5 Gy₁₀ and 58.5 Gy₁₀, respectively (P < 0.001 in total SBRT vs. 3DCRT, P < 0.001 in CK vs. 3DCRT, P = 0.004 in TB vs. 3DCRT). The tumor response rates were 67%, 70%, 62% and 46%, respectively (P = 0.04, P = 0.04, P = 0.25). The 1-year overall survival rates were 49.3%, 56.7%, 38.1% and 29.3%, respectively (P = 0.02, P = 0.02, P = 0.30), and the 1-year local progression rates were 20.4%, 21.9%, 18.8% and 43.6%, respectively (P = 0.01, P = 0.04, P = 0.10). The use of SBRT made it possible to achieve a higher BED₁₀ compared with the use of 3DCRT. Improvements in local control and survival were achieved in the CK group and the total SBRT group. Our results suggest that SBRT may have the potential to be the standard RT technique for the treatment of PVTT/IVCTT.

Keywords: hepatocellular carcinoma; inferior vena cava tumor thrombosis; portal vein tumor thrombosis; stereotactic body radiotherapy; three-dimensional conformal radiotherapy.

Fig. 1.

An example of the dose distribution and the DVH comparing CK, TB and 3DCRT in the patients who had PVTTs invading the main trunk. A total dose of 51 Gy in 12 fractions, and of 45 Gy in 15 fractions was delivered to the PVTT using a prescription of PTV D95 in the CK case and TB case, respectively. In the 3DCRT cases, 45 Gy in 15 fractions was prescribed to the isocenter of the PTV. Liver V20 in CK, TB and 3DCRT was 12.5%, 13.1% and 25.9%, respectively. Normal liver D_mean was 11.0 Gy, 8.5 Gy and 17.3 Gy, respectively. Dose to 700 cc uninvolved liver was 9.7 Gy, 11.2 Gy, and 15.0 Gy, respectively. Intestine D_max was 28.0 Gy, 38.9 Gy and 39.5 Gy, respectively.

Fig. 2.

OS for patients treated with SBRT and 3DCRT. (a) with CK, TB and 3DCRT. (b) LP rate of PVTT/IVCTT for patients treated with SBRT and 3DCRT. (c) With CK, TB and 3DCRT. (d) A significant difference in OS and LF rates is observed between the total SBRT group and the 3DCRT group (P = 0.02 and 0.01, respectively), and between the CK group and the 3DCRT group (P = 0.02 and 0.04, respectively).