Page 495 - Read Online

Page 2 of 12 Zeng et al. Hepatoma Res2020;6:43 I http://dx.doi.org/10.20517/2394-5079.2020.29

INTRODUCTION
Recent technological advances offer precise and safe radiation delivery to tumors in various areas of the
body through imaging guidance. External beam radiation therapy (EBRT) has been recommended as
a therapeutic option for HCCs that are considered unresectable according to National Comprehensive
Cancer Network guidelines because of the tumor’s location, inadequate hepatic reserve, or the presence of
comorbidities. SBRT is a type of EBRT technique requiring special equipment for patient positioning and
the delivery of high-dose radiation to tumors. There is growing evidence supporting the usefulness of SBRT
for patients considered unsuitable for hepatectomy or RFA. However, most oncologists or hepatologists do
not understand this treatment technique because of limited use of SBRT in their clinical practice. Herein,
we discuss 11 typical patients with HCC to clarify the indications, therapeutic outcomes, treatment-related
toxicities, and doses of SBRT, as well as the expected post-SBRT imaging features.

DEFINITIONS
SBRT is an advanced technique of hypofractionated EBRT with photons, which delivers large ablative doses
of radiation to tumors. This complex technique relies on the following: (1) stringent control of breathing
motion for liver cancer, using four-dimensional computed tomography scans to track respiration-induced
hepatic movement; (2) extremely precise patient positioning; and (3) image guidance for radiation delivery.

Early-stage HCC is defined as a solitary tumor with a maximum diameter ≤ 5 cm or multiple nodules
(≤ 3 total), each with a maximum diameter ≤ 3 cm, without vascular invasion or extrahepatic metastasis
and accompanied by Child-Pugh Class A or B hepatic function (Cases 1-3 and 5). Not all small tumors
are classified as early-stage because some have decreased in size after treatment (Case 8). If intrahepatic
recurrence (Cases 9 and 10) or Child-Pugh Class C (Case 11) function is present, HCC is considered later
stage.

CLINICAL EFFECTIVENESS OF SBRT FOR HCC
There is a growing body of evidence indicating the usefulness of SBRT for the management of patients with
HCC. We conducted a literature review and identified several retrospective studies involving the use of SBRT
for HCC. These studies have primarily included patients in whom surgical resection or RFA was difficult,
unfeasible, or rejected, as well as some patients with intermediate- or advanced-stage HCC. The results of
these studies are summarized in Table 1. This table is restricted to studies involving the use of ≤ 10 fractions
of SBRT.

Overall survival
As shown in Table 1, overall survival (OS) rates have varied between studies. For early-stage HCC, 2-year
[2,3]
[1,2]
OS rates of 78%-80% , 3-year OS rates of 66%-73% , and a 5-year OS rate of 64% after SBRT have been
[3]
reported .
Local tumor control
As shown in Table 1, local tumor control rates at one and two years were approximately 95% in most studies,
especially those reported in more recent years [1-13] .

Bridging before liver transplantation
[14]
SBRT is suitable bridging therapy for patients with HCC awaiting liver transplantation. Sapisochin et al.
compared the efficacy of SBRT, TACE, and RFA as a bridge to transplantation in a large cohort of patients
with HCC and concluded that SBRT can be a safe alternative to the other, more conventional bridging
therapies. However, SBRT has been safer than RFA and TACE when ascites or poor coagulation function are
present, as often occurs in patients with underlying liver disease.