Yonsei Med J.  2018 Oct;59(8):912-922. 10.3349/ymj.2018.59.8.912.

Stereotactic Body Radiotherapy: Does It Have a Role in Management of Hepatocellular Carcinoma?

• Choi SH
• Seong J

• KMID: 2419724
• DOI: http://doi.org/10.3349/ymj.2018.59.8.912

Abstract

Stereotactic body radiotherapy (SBRT) is a form of radiotherapy that delivers high doses of irradiation with high precision in a small number of fractions. However, it has not frequently been performed for the liver due to the risk of radiation-induced liver toxicity. Furthermore, liver SBRT is cumbersome because it requires accurate patient repositioning, target localization, control of breathing-related motion, and confers a toxicity risk to the small bowel. Recently, with the advancement of modern technologies including intensity-modulated RT and image-guided RT, SBRT has been shown to significantly improve local control and survival outcomes for hepatocellular carcinoma (HCC), specifically those unfit for other local therapies. While it can be used as a stand-alone treatment for those patients, it can also be applied either as an alternative or as an adjunct to other HCC therapies (e.g., transarterial chemoembolization, and radiofrequency ablation). SBRT might be an effective and safe bridging therapy for patients awaiting liver transplantation. Furthermore, in recent studies, SBRT has been shown to have a potential role as an immunostimulator, supporting the novel combination strategy of immunoradiotherapy for HCC. In this review, the role of SBRT with some technical issues is discussed. In addition, future implications of SBRT as an immunostimulator are considered.

Keyword

Hepatocellular carcinoma; liver tumors; radiotherapy; stereotactic body radiotherapy; intensity-modulated radiotherapy; immunotherapy

MeSH Terms

Carcinoma, Hepatocellular*
Humans
Immunotherapy
Liver
Liver Transplantation
Moving and Lifting Patients
Radioimmunotherapy
Radiosurgery*
Radiotherapy
Radiotherapy, Intensity-Modulated

Figure

• 

  Fig. 1 CT scans of patient cases showing objective responses to SBRT of 60 Gy in 4 fractions for HCC. (A) Before SBRT, the CT scan showed a 3 cm-sized viable HCC after multiple TACE treatments at the dome of the liver (white arrows) (AFP/PIVKA-II: 1017 ng/mL/95 mAU/mL). (B) After SBRT, the 1-year post-SBRT CT scan showed radiologic CR with significantly decreased tumor markers approximating normal levels (AFP/PIVKA-II: 2.04 ng/mL/14 mAU/mL). (C) Before SBRT, a 4 cm-sized HCC was observed in the left lobe (white arrows) (AFP/PIVKA-II: 6.14 ng/mL/31 mAU/mL). (D) After SBRT, the 4-month post-SBRT CT scan showed radiologic CR with further reduced tumor marker levels (AFP/PIVKA-II: 3.38 ng/mL/31 mAU/mL). SBRT, stereotactic-body radiotherapy; HCC, hepatocellular carcinoma; TACE, transarterial chemoembolization; AFP, alpha-fetoprotein; PIVKA-II, prothrombin-induced by vitamin K absence or antagonist-II; CR, complete response.

• 

  Fig. 2 Different motion management methods in RT. (A) The motion-encompassing method refers to the covering of all possible positions of the moving tumor through the whole breathing cycle using 4D-CT images. Subsequently, a large volume of normal tissue may be irradiated. (B) The breath-hold method refers to let the patient hold breaths for a few seconds under deep inspiration, and then deliver the radiation only when the liver is in a certain position. (C) The forced shallow breathing is a method of using a special external device such as an abdominal compressor to allow the patient to breathe shallow during radiation therapy. Although breath-hold and forced shallow breathing might result in patient discomfort or inconvenience during treatment, it can reduce the respiratory motion for liver tumors and enhance the accuracy. (D) The respiratory gating method is a method of turning on the radiation beam only during a specific respiratory cycle, after accurately grasping the position of a tumor according to a patient's respiratory cycle in advance using 4D-CT images. (E) The real-time tracking method refers to tracking the movement of the tumor along the respiratory cycle using the surrogate on the abdominal surface or internal fiducial marker and then delivering the radiation following the tumor inside the body. No respiratory control and abdominal compression are needed. RT, radiotherapy; 4D, four-dimensional.

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