Safety and Efficacy of Accelerated Hypofractionation and Stereotactic Body Radiation Therapy for Hepatocellular Carcinoma Patients With Varying Degrees of Hepatic Impairment

DCE-MRI functional NTCP modeling in SBRT for hepatocellular carcinoma

PURPOSE

To develop a function-guided normal tissue complication probability (NTCP) model to predict the risk of ALBI grade increases in patients treated with stereotactic body radiotherapy (SBRT) for hepatocellular carcinoma (HCC).

METHODS

Voxelized contrast kinetic modeling was performed on pre-treatment dynamic contrast enhanced (DCE) MRI employing gadoxetate disodium contrast to create volumetric maps correlated with liver function. Hepatic NTCP modeling was performed using a local-damage parallel-architecture model with ALBI grade increase as endpoint. Each voxel was assigned a damage probability (logistic function: EQD50,k). A weighted organ-average fraction of damaged subunits is calculated using the functional metric's cumulative distribution function. NTCPRTfrom SBRT is calculated using a shifted error function (µ, σ) and combined with baseline NTCP0.

RESULTS

NTCP modelling was performed using retrospective data from 68 patients. Local damage model parameters were obtained to be EQD50,k=17Gy2,1.68, while NTCP parameters were μ,σ,NTCP0=0.47,0.12,13%. The total number of observed ALBI grade increases were 11/68 patients (16 %). In 63 patients (93 %) the estimated damaged liver fraction was fdmg<0.3 with nine NTCP events (14.2 %). The remaining 5 patients accounted for two NTCP events (40 %).

CONCLUSIONS

NTCP modelling using weighting of functional subunit damage probabilities has the potential to be superior in predicting ALBI grade increases after SBRT for HCC compared to function-agnostic modeling. 3D maps of surrogate quantities for liver function could, within limitations, guide external beam SBRT optimization.

Feasibility study of modularized pin ridge filter implementation in proton FLASH planning for liver stereotactic ablative body radiotherapy

Objective.We previously developed a FLASH planning framework for streamlined pin-ridge-filter (pin-RF) design, demonstrating its feasibility for single-energy proton FLASH planning. In this study, we refined the pin-RF design for easy assembly using reusable modules, focusing on its application in liver stereotactic ablative body radiotherapy (SABR).Approach.This framework generates an intermediate intensity-modulated proton therapy (IMPT) plan and translates it into step widths and thicknesses of pin-RFs for a single-energy FLASH plan. Parameters like energy spacing, monitor unit limit, and spot quantity were adjusted during IMPT planning, resulting in pin-RFs assembled using predefined modules with widths from 1 to 6 mm, each with a water-equivalent-thickness of 5 mm. This approach was validated on three liver SABR cases. FLASH doses, quantified using the FLASH effectiveness model at 1-5 Gy thresholds, were compared to conventional IMPT (IMPT-CONV) doses to assess clinical benefits.Main results.The highest demand for 6 mm width modules, moderate for 2-4 mm, and minimal for 1- and 5-mm modules were shown across all cases. At lower dose thresholds, the two-beam case reduced indicators including liverV21Gyand skinDmaxby >19.4%, while the three-beam cases showed reductions⩽11.4%, indicating the need for higher fractional beam doses for an enhanced FLASH effect. Positive clinical benefits were seen only in the two-beam case at the 5 Gy threshold. At the 1 Gy threshold, the two-beam FLASH plan outperformed the IMPT-CONV plan, reducing dose indicators for all relevant normal tissues by up to 31.2%. In contrast, the three-beam cases showed negative clinical benefits, with skinDmaxand liverV21Gyincreasing by up to 17.4% due to lower fractional beam doses and closer beam arrangements.Significance.This study evaluated the feasibility of modularizing streamlined pin-RFs in single-energy proton FLASH planning for liver SABR, offering guidance on optimal module composition and strategies to enhance FLASH planning.

Evidence-based clinical recommendations for hypofractionated radiotherapy: exploring efficacy and safety - Part 4: Liver and locally recurrent rectal cancer

In this paper, we review the use of hypofractionated radiotherapy for gastrointestinal malignancies, focusing on primary and metastatic liver cancer, and recurrent rectal cancer. Technological advancements in radiotherapy have facilitated the direct delivery of high-dose radiation to tumors, while limiting normal tissue exposure, supporting the use of hypofractionation. Hypofractionated radiotherapy is particularly effective for primary and metastatic liver cancer where high-dose irradiation is crucial to achieve effective local control. For recurrent rectal cancer, the use of stereotactic body radiotherapy offers a promising approach for re-irradiation, balancing efficacy and safety in patients who have been administered previous pelvic radiotherapy and in whom salvage surgery is not applicable. Nevertheless, the potential for radiation-induced liver disease and gastrointestinal complications presents challenges when applying hypofractionation to gastrointestinal organs. Given the lack of universal consensus on hypofractionation regimens and the dose constraints for primary and metastatic liver cancer, as well as for recurrent rectal cancer, this review aims to facilitate clinical decision-making by pointing to potential regimens and dose constraints, underpinned by a comprehensive review of existing clinical studies and guidelines.

Development and validation of a nomogram for radiation-induced hepatic toxicity after intensity modulated radiotherapy for hepatocellular carcinoma: a retrospective study

OBJECTIVE

This study aimed to construct a nomogram to predict radiation-induced hepatic toxicity in patients with hepatocellular carcinoma treated with intensity-modulated radiotherapy.

METHODS

This study reviewed the clinical characteristics and dose-volume parameters of 196 patients with hepatocellular carcinoma. Radiation-induced hepatic toxicity was defined as progression of the Child-Pugh score caused by intensity-modulated radiotherapy. Factors relevant to radiation-induced hepatic toxicity were selected using receiver operating characteristic and univariate logistic analysis. A risk assessment model was developed, and its discrimination was validated.

RESULTS

Eighty-eight (44.90%) and 28 (14.29%) patients had radiation-induced hepatic toxicity ≥ 1 (Child-Pugh ≥ 1) and radiation-induced hepatic toxicity ≥ 2 (Child-Pugh ≥ 2). Pre-treatment Child-Pugh, body mass index and dose-volume parameters were correlated with radiation-induced hepatic toxicity ≥ 1 using univariate logistic analysis. V15 had the best predictive effectiveness among the dose-volume parameters in both the training (area under the curve: 0.763, 95% confidence interval: 0.683-0.842, P < 0.001) and validation cohorts (area under the curve: 0.759, 95% confidence interval: 0.635-0.883, P < 0.001). The area under the curve values of the model that was constructed by pre-treatment Child-Pugh, body mass index and V15 for radiation-induced hepatic toxicity ≥1 were 0.799 (95% confidence interval: 0.719-0.878, P < 0.001) and 0.775 (95% confidence interval: 0.657-0.894, P < 0.001) in the training and validation cohorts, respectively. Patients with a body mass index ≤ 20.425, Barcelona clinic liver cancer = C, Hepatitis B Virus-positive, Eastern Cooperative Oncology Group = 1-2 and hepatic fibrosis require lower V15 dose limits.

CONCLUSIONS

Risk assessment model constructed from Pre-treatment Child-Pugh, V15 and body mass index can guide individualized patient selection of toxicity minimization strategies.

Optimal hypofractionated radiation therapy schemes for early-stage hepatocellular carcinoma

PURPOSE

Stereotactic body radiation therapy (SBRT) has been emerging as an efficacious and safe treatment modality for early-stage hepatocellular carcinoma (HCC), but optimal fractionation regimens are unknown. This study aims to analyze published clinical tumor control probability (TCP) data as a function of biologically effective dose (BED) and to determine radiobiological parameters and optimal fractionation schemes for SBRT and hypofractionated radiation therapy of early-stage HCC.

MATERIAL AND METHODS

Clinical 1- to 5-year TCP data of 4313 patients from 41 published papers were collected for hypofractionated radiation therapy at 2.5-4.5 Gy/fraction and SBRT of early-stage HCC. BED was calculated at isocenter using three representative radiobiological models developed per the Hypofractionated Treatment Effects in the Clinic (HyTEC) initiative. Radiobiological parameters were determined from a fit to the TCP data using the least χ2 method with one set of model parameters regardless of tumor stages or Child-Pugh scores A and B.

RESULTS

The fits to the clinical TCP data for SBRT of early-stage HCC found consistent α/β ratios of about 14 Gy for all three radiobiological models. TCP increases sharply with BED and reaches an asymptotic maximal plateau, which results in optimal fractionation schemes of least doses to achieve asymptotic maximal tumor control for SBRT and hypofractionated radiation therapy of early-stage HCC that are found to be model-independent.

CONCLUSION

From the fits to the clinical TCP data, we presented the first determination of radiobiological parameters and model-independent optimal fractionation regimens in 1-20 fractions to achieve maximal tumor control whenever safe for SBRT and hypofractionated radiation therapy of early-stage HCC. The determined optimal fractionation schemes agree well with clinical practice for SBRT of early-stage HCC. However, most existing hypofractionated radiation therapy schemes of 3-5 Gy/fraction are not optimal, higher doses are required to maximize tumor control, further validation of these findings is essential with clinical TCP data.

Liver stereotactic body radiation therapy without fiducial or retained ethiodized oil guidance warrants greater than 5 mm planning target volumes

INTRODUCTION

For liver stereotactic body radiation therapy (SBRT), the placement of fiducial markers or retained ethiodized oil by transarterial chemoembolisation (TACE) provides a landmark for consistent target localisation. TACE and fiducial markers are invasive procedures that harbour additional risks. We hypothesise that liver SBRT can be accurately delivered without the use of these invasive surrogate markers.

METHODS

We retrospectively identified 50 consecutive patients who underwent liver SBRT with respiratory motion management to a single lesion which exhibited retained ethiodized oil per prior TACE delivery. For each SBRT fraction, two manual rigid image registrations were performed by the treating physician. One using the liver contour as a surrogate for the target and second aligning only to the radio-opaque retained ethiodized oil of the treated lesion. The magnitude of the displacement vector between the two registration methods was used to assess the accuracy of target localisation if ethiodized oil was not present.

RESULTS

For the 50 patients, a total of 244 analysable cone-beam CTs (CBCTs) were included (six CBCTs excluded due to poor ethiodized oil visualisation). Respiratory motion management techniques consisted of active breathing control for 13 and abdominal compression for 37 patients. Forty-two patients had peripheral lesions and eight had central lesions (<2 cm from left and right portal veins). The average target localisation offset between the two registration methods (i.e. liver contour vs. retained ethiodized oil alignment) for patients with a single peripheral or central liver lesion was 5.8 and 5.3 mm, respectively.

CONCLUSIONS

Across all patients, the average change in target position exceeded 5 mm for image registration methods based on the liver contour alone versus the retained ethiodized oil region. This suggests that margins greater than 5 mm may be required for respiratory motion-managed liver SBRT treatments in patients who do not undergo prior TACE or fiducial placement.

Time variation of high-risk groups for liver function deteriorations within fluctuating long-term liver function after hepatic radiotherapy in patients with hepatocellular carcinoma

PURPOSE

The purpose of this study is to find essential risk factors associated with liver function (LF) deteriorations within fluctuating long-term LF and their time-varying effects in patients with hepatocellular carcinoma (HCC) receiving hepatic radiotherapy and to identify high-risk groups for adverse LF deteriorations and their changes over time in facilitating the prevention of hepatic decompensation and the improvement of survival.

MATERIALS AND METHODS

A total of 133 HCC patients treated by hepatic radiotherapy were enrolled. A study design was conducted to convert posttreatment long-term LF with fluctuating levels over time to recurrent LF events using defined upgrades in a grading scale. The hazard ratios (HR) of pretreatment biochemical, demographic, clinical, and dosimetric factors in developing posttreatment LF events were estimated using the Cox model. Methodologies of the counting process approach, robust variance estimation, goodness-of-fit testing based on the Schoenfeld residuals, and time-dependent covariates in survival analysis were employed to handle the correlation within subjects and evaluate the time-varying effects during long-term follow-up.

RESULTS

Baseline LF score before radiotherapy and gender were significant factors. Initial HR in developing LF events was 1.17 (95% CI 1.11-1.23; P < 0.001) for each increase of baseline LF score and kept almost constant over time (HR, 1.00; 95% CI 1.00-1.01; P = 0.065). However, no difference was observed regarding initial hazards for gender (HR, 1.00; 95% CI 0.64-1.56; P = 0.994), but the hazard for women got higher monthly over time compared with men (HR, 1.04; 95% CI 1.01-1.07; P = 0.006).

CONCLUSIONS

High-risk groups for adverse LF deteriorations after hepatic radiotherapy may change over time. Patients with poor baseline LF are vulnerable from the beginning. Women require prevention strategies and careful monitoring for deteriorations at a later stage.

Low-dose radiotherapy combined with dual PD-L1 and VEGFA blockade elicits antitumor response in hepatocellular carcinoma mediated by activated intratumoral CD8+ exhausted-like T cells

Atezolizumab (anti-PD-L1) combined with bevacizumab (anti-VEGFA) is the first-line immunotherapy for advanced hepatocellular carcinoma (HCC), but the number of patients who benefit from this regimen remains limited. Here, we combine dual PD-L1 and VEGFA blockade (DPVB) with low-dose radiotherapy (LDRT), which rapidly inflames tumors, rendering them vulnerable to immunotherapy. The combinatorial therapy exhibits superior antitumor efficacy mediated by CD8+ T cells in various preclinical HCC models. Treatment efficacy relies upon mobilizing exhausted-like CD8+ T cells (CD8+ Tex) with effector function and cytolytic capacity. Mechanistically, LDRT sensitizes tumors to DPVB by recruiting stem-like CD8+ Tpex, the progenitor exhausted CD8+ T cells, from draining lymph nodes (dLNs) into the tumor via the CXCL10/CXCR3 axis. Together, these results further support the rationale for combining LDRT with atezolizumab and bevacizumab, and its clinical translation.

A Phase II Study of Optimized Individualized Adaptive Radiotherapy for Hepatocellular Carcinoma

PURPOSE

We hypothesized that optimizing the utility of stereotactic body radiotherapy (SBRT) based on the individual patient's probability for tumor control and risk of liver injury would decrease toxicity without sacrificing local control in patients with impaired liver function or tumors not amenable to thermal ablation.

PATIENTS AND METHODS

Patients with Child-Pugh (CP) A to B7 liver function with aggregate tumor size >3.5 cm, or CP ≥ B8 with any size tumor were prospectively enrolled on an Institutional Review Board-approved phase II clinical trial to undergo SBRT with baseline and midtreatment dose optimization using a quantitative, individualized utility-based analysis. Primary endpoints were change in CP score of ≥2 points within 6 months and local control. Protocol-treated patients were compared with patients receiving conventional SBRT at another cancer center using overlap weighting.

RESULTS

A total of 56 patients with 80 treated tumors were analyzed with a median follow-up of 11.2 months. Two-year cumulative incidence of local progression was 6.4% [95% confidence interval (CI, 2.4-13.4)]. Twenty-one percent of patients experienced treatment-related toxicity within 6 months, which is similar to the rate for SBRT in patients with CP A liver function. An analysis using overlap weighting revealed similar local control [HR, 0.69; 95% CI (0.25-1.91); P = 0.48] and decreased toxicity [OR, 0.26; 95% CI (0.07-0.99); P = 0.048] compared with conventional SBRT.

CONCLUSIONS

Treatment of individuals with impaired liver function or tumors not amenable to thermal ablation with a treatment paradigm designed to optimize utility may decrease treatment-related toxicity while maintaining tumor control.

Evolution of Response-Based Radiotherapy for Hepatocellular Cancer

ABSTRACT

Stereotactic body radiation therapy has emerged as a safe and effective treatment modality for properly selected hepatocellular cancer (HCC) patients with normal liver function. However, many HCC patients have reduced baseline liver function due to underlying cirrhosis or prior liver-directed therapies. Therefore, because of the increased risk of hepatotoxicity, the use of stereotactic body radiation therapy for patients with reduced liver function has been approached with caution. Individualized, response-based radiotherapy incorporates models, imaging tools, and biomarkers that determine the dose-response relationship of the liver before, during, and after treatment and has been useful in reducing the likelihood of liver damage without sacrificing tumor control. This review discusses the evolution of response-based radiotherapy for HCC and highlights areas for further investigation.

Advances in Radiation Therapy for Primary Liver Cancer

During the past 30 years, several advances have been made allowing for safer and more effective treatment of patients with liver cancer. This report reviews recent advances in radiation therapy for primary liver cancers including hepatocellular carcinoma and intrahepatic cholangiocarcinoma. First, studies focusing on liver stereotactic body radiation therapy (SBRT) are reviewed focusing on lessons learned and knowledge gained from early pioneering trials. Then, new technologies to enhance SBRT treatments are explored including adaptive therapy and MRI-guided and biology-guided radiation therapy. Finally, treatment with Y-90 transarterial radioembolization is reviewed with a focus on novel approaches focused on personalized therapy.

Use of single-energy proton pencil beam scanning Bragg peak for intensity-modulated proton therapy FLASH treatment planning in liver hypofractionated radiation therapy

PURPOSE

The transmission proton FLASH technique delivers high doses to the normal tissue distal to the target, which is less conformal compared to the Bragg peak technique. To investigate FLASH RT planning using single-energy Bragg peak beams with a similar beam arrangement as clinical intensity-modulated proton therapy (IMPT) in liver stereotactic body radiation therapy (SBRT) and to characterize the plan quality, dose sparing of organs-at-risk (OARs), and FLASH dose rate percentage.

MATERIALS AND METHODS

An in-house platform was developed to enable inverse IMPT-FLASH planning using single-energy Bragg peaks. A universal range shifter and range compensators were utilized to effectively align the Bragg peak to the distal edge of the target. Two different minimum MU settings of 400 and 800 MU/spot (Bragg-400MU and Bragg-800MU) plans were investigated on 10 consecutive hepatocellular carcinoma patients previously treated by IMPT-SBRT to evaluate the FLASH dose and dose rate coverage for OARs. The IMPT-FLASH using single-energy Bragg peaks delivered 50 Gy in 5 fractions with similar or identical beam arrangement to the clinical IMPT-SBRT plans. NRG GI003 dose constraint metrics were used. Three dose rate calculation methods, including average dose rate (ADR), dose threshold dose rate (DTDR), and dose-averaged dose rate (DADR), were all studied.

RESULTS

The novel spot map optimization can fulfill the inverse planning using single-energy Bragg peaks. All the Bragg peak FLASH plans achieved similar results for the liver-GTV D_mean and heart D_0.5cc , compared to SBRT-IMPT. The Bragg-800MU plans resulted in 18.3% higher CTV D_2cc compared with SBRT (p < 0.05), and no significant difference was found between Bragg-400MU and SBRT plans. For the CTV D_max , SBRT plans resulted in 10.3% (p<0.01) less than Bragg-400MU plans and 16.6% (p<0.01) less than Bragg-800MU plans. The Bragg-800MU plans generally achieved higher ADR, DADR, and DTDR dose rates than Bragg-400MU plans, and DADR mostly led to the highest V_40Gy/s compared to other dose rate calculation methods, whereas ADR led to the lowest. The lower dose rate portions in certain OARs are related to the lower dose deposited due to the farther distances from targets, especially in the penumbra of the beams.

CONCLUSION

Single-energy Bragg peak IMPT-FLASH plans eliminate the exit dose in normal tissues, maintaining comparable dose metrics to the conventional IMPT-SBRT plans while achieving a sufficient FLASH dose rate for liver cancers. This study demonstrates the feasibility of and sufficiently high dose rate when applying Bragg peak FLASH treatment for liver cancer hypofractionated FLASH therapy. The advancement of this novel method has the potential to optimize treatment for liver cancer patients. This article is protected by copyright. All rights reserved.

Hypofractionation in Hepatocellular Carcinoma - The Effect of Fractionation Size

The use of stereotactic body radiotherapy (SBRT) in hepatocellular carcinoma (HCC) has increased over the years. Several prospective studies have demonstrated its safety and efficacy, and randomised trials are underway. The advancement in technology has enabled the transition from three-dimensional conformal radiotherapy to highly focused SBRT. Liver damage is the primary limiting toxicity with radiation, with the incidence of grade 3 varying from 0 to 30%. The reported radiotherapy fractionation schedule for HCC, and in practice use, ranges from one to 10 fractions, based on clinician preference and technology available, tumour location and tumour size. This review summarises the safety and efficacy of various SBRT fractionation schedules for HCC.

Is hepatocellular carcinoma complicated with portal vein tumor thrombosis potentially curable by radiotherapy in the form of stereotactic body radiation therapy?

PURPOSE

The prognosis of hepatocellular carcinoma (HCC) with portal vein tumor thrombosis (PVTT) is dismal. Despite best treatment and care, the patients with this malignancy only showed 2.7-4 months of overall survival. It is debatable whether liver transplantation helps PVTT sufferers. The effectiveness of radiation therapy in treating HCC patients with PVTT should not be undervalued. By limiting the high dosage region to a small planning target volume, stereotactic radiation delivery has shifted toward hypofractionation, limiting the radiation exposure to healthy organs and tissues. Stereotactic body radiotherapy (SBRT) has a local control rate of 75-100%, depending on the treatment. The major limitation in SBRT for hepatocellular carcinoma with PVTT is the paucity of prospective evidence for longer periods beyond the first two years after treatment. More prospective studies/randomized clinical trials with a longer follow-up, larger sample size, and adequate statistical power are the dire need of the present situation to ascertain the curative effect of SBRT as primary therapy for advanced HCC with PVTT.

CONCLUSION

SBRT can improve survival, particularly for patients receiving multidisciplinary treatment. This review sums up our most current understanding of how radiation therapy, notably SBRT, can be used to treat hepatocellular carcinoma when combined with PVTT. Recent research has led us to believe that irradiation in the form of SBRT may cure hepatocellular carcinoma complicated by PVTT.

Does stereotactic body radiation improve outcomes compared to conventional radiation for liver cancer patients?

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There has been a paradigm shift to SBRT without evidence that these high-dose ultra-low fractions result in improved outcomes.

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This prospective cohort compares the survival of patients treated with conventional versus SBRT treatments for liver tumours.

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The SBRT group received an average of 5 fractions, and the conventional group received an average of 17 fractions.

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397 patients were included. Overall survival was higher for SBRT patients at the 2-year time point (42% vs 27% p = 0.01).

Introduction

Methods

Results

Conclusion

FLASH Radiotherapy Using Single-Energy Proton PBS Transmission Beams for Hypofractionation Liver Cancer: Dose and Dose Rate Quantification

PURPOSE

This work aims to study the dose and ultra-high-dose rate characteristics of transmission proton pencil beam scanning (PBS) FLASH radiotherapy (RT) for hypofractionation liver cancer based on the parameters of a commercially available proton system operating under FLASH mode.

METHODS AND MATERIALS

An in-house treatment planning software (TPS) was developed to perform intensity-modulated proton therapy (IMPT) FLASH-RT planning. Single-energy transmission proton PBS plans of 4.5 Gy × 15 fractions were optimized for seven consecutive hepatocellular carcinoma patients, using 2 and 5 fields combined with 1) the minimum MU/spot chosen between 100 and 400, and minimum spot time (MST) of 2 ms, and 2) the minimum MU/spot of 100, and MST of 0.5 ms, based upon considerations in target uniformities, OAR dose constraints, and OAR FLASH dose rate coverage. Then, the 3D average dose rate distribution was calculated. The dose metrics for the mean dose of Liver-GTV and other major OARs were characterized to evaluate the dose quality for the different combinations of field numbers and minimum spot times compared to that of conventional IMPT plans. Dose rate quality was evaluated using 40 Gy/s volume coverage (V40Gy/s).

RESULTS

All plans achieved favorable and comparable target uniformities, and target uniformity improved as the number of fields increased. For OARs, no significant dose differences were observed between plans of different field numbers and the same MST. For plans using shorter MST and the same field numbers, better sparing was generally observed in most OARs and was statistically significant for the chest wall. However, the FLASH dose rate coverage V40Gy/s was increased by 20% for 2-field plans compared to 5-field plans in most OARs with 2-ms MST, which was less evident in the 0.5-ms cases. For 2-field plans, dose metrics and V40Gy/s of select OARs have large variations due to the beam angle selection and variable distances to the targets. The transmission plans generally yielded inferior dosimetric quality to the conventional IMPT plans.

CONCLUSION

This is the first attempt to assess liver FLASH treatment planning and demonstrates that it is challenging for hypofractionation with smaller fractional doses (4.5 Gy/fraction). Using fewer fields can allow higher minimum MU/spot, resulting in higher OAR FLASH dose rate coverages while achieving similar plan quality compared to plans with more fields. Shorter MST can result in better plan quality and comparable or even better FLASH dose rate coverage.

External Beam Radiation Therapy for Primary Liver Cancers: An ASTRO Clinical Practice Guideline

PURPOSE

This guideline provides evidence-based recommendations for the indications and technique-dose of external beam radiation therapy (EBRT) in hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (IHC).

METHODS

The American Society for Radiation Oncology convened a task force to address 5 key questions focused on the indications, techniques, and outcomes of EBRT in HCC and IHC. This guideline is intended to cover the definitive, consolidative, salvage, preoperative (including bridge to transplant), and adjuvant settings as well as palliative EBRT for symptomatic primary lesions. Recommendations were based on a systematic literature review and created using a predefined consensus-building methodology and system for grading evidence quality and recommendation strength.

RESULTS

Strong recommendations are made for using EBRT as a potential first-line treatment in patients with liver-confined HCC who are not candidates for curative therapy, as consolidative therapy after incomplete response to liver-directed therapies, and as a salvage option for local recurrences. The guideline conditionally recommends EBRT for patients with liver-confined multifocal or unresectable HCC or those with macrovascular invasion, sequenced with systemic or catheter-based therapies. Palliative EBRT is conditionally recommended for symptomatic primary HCC and/or macrovascular tumor thrombi. EBRT is conditionally recommended as a bridge to transplant or before surgery in carefully selected patients. For patients with unresectable IHC, consolidative EBRT with or without chemotherapy should be considered, typically after systemic therapy. Adjuvant EBRT is conditionally recommended for resected IHC with high-risk features. Selection of dose-fractionation regimen and technique should be based on disease extent, disease location, underlying liver function, and available technologies.

CONCLUSIONS

The task force has proposed recommendations to inform best clinical practices on the use of EBRT for HCC and IHC with strong emphasis on multidisciplinary care. Future studies should focus on further defining the role of EBRT in the context of liver-directed and systemic therapies and refining optimal regimens and techniques.

Evaluation of Pretreatment Magnetic Resonance Elastography for the Prediction of Radiation-Induced Liver Disease

Purpose

Magnetic resonance (MR) elastography (E) is a noninvasive technique for quantifying liver stiffness (LS) for fibrosis. This study evaluates whether LS is associated with risk of developing radiation-induced liver disease (RILD) in patients receiving liver-directed radiation therapy (RT).

Methods and Materials

Based on prior studies, LS ≤3 kPa was considered normal and LS >3.0 kPa as representing fibrosis. RILD was defined as an increase in Child-Pugh (CP) score of ≥2 from baseline within 1 year of RT. Univariate and multivariate Cox models were used to assess correlation.

Results

One hundred two patients, 51 with primary liver tumors and 51 with liver metastases, were identified with sufficient follow-up. In univariate models, pre-RT LS >3.0 kPa (hazard ratio [HR] 4.9; 95% confidence interval [CI], 1.6-14; P = .004), body mass index (BMI), clinical cirrhosis, CP score, albumin-bilirubin (ALBI) grade 2, primary liver tumor, and mean liver dose were significantly associated with risk of post-RT RILD. In a multivariate analysis, LS >3.0 and mean liver dose both were significantly associated with RILD risk.

Conclusions

Elevated pre-RT LS is associated with an increased risk of RILD in patients receiving liver-directed RT.

Survival and morbidity following stereotactic radiotherapy of hepatocellular carcinoma: a ten-year, single institution experience

BACKGROUND AND AIM

Stereotactic ablative body radiotherapy (SABR) is an emerging treatment option in hepatocellular carcinoma (HCC) in patients ineligible for other local ablative therapies. This study reports on the safety and efficacy of SABR in a Danish cohort of HCC patients.

MATERIALS AND METHODS

Between January 2009 and December 2018, 28 patients with HCCs were treated with SABR at our institution. The primary endpoint of this retrospective study was local control; secondary endpoints were progression-free survival, overall survival and toxicity.

RESULTS

In 28 patients, 32 tumors (median size 3.7 cm, range 1.4-6.8 cm) were treated. The median follow-up time was 16 months. Most patients (68%) received previous liver-directed treatments. A dose of 48 Gy in three or six fractions were given to 43% of the patients. Grad 1 or 2 toxicity was reported in 13 patients (46%), whereas 4 patients (14%) needed hospitalization (grade 3). One-year local control and overall survivals were 90% and 71%, respectively. One-year progression-free survival was 32%, and 65% of patients with disease progression received further HCC therapy. In univariate analysis, none of the examined factors predicted recurrence or overall survival.

CONCLUSION

SABR provides high local control to inoperable HCC. SABR can be delivered safely even after previous liver-directed therapies and subsequent therapies are feasible after treatment with SABR. Despite excellent local control, disease progression outside of the irradiated site remains prominent. Further studies are warranted to examine combined therapy approaches to maximize disease control.

TNFR1 and the TNFα axis as a targetable mediator of liver injury from stereotactic body radiation therapy

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Elevated soluble TNFR1 levels are predictive of liver toxicity among patients receiving radiation.

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Soluble TNFR1 levels do not independently predict liver toxicity when included in models with ALBI and mean liver dose.

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Data suggest that liver inflammation mediates toxicity after liver irradiation and that the TNFα axis is associated with this inflammation.

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Future studies of should evaluate approaches that target pre-treatment inflammation to reduce the risk of toxicity.

Introduction

Radiation therapy for the management of intrahepatic malignancies can adversely affect liver function. Liver damage has been associated with increased levels of inflammatory cytokines, including tumor necrosis factor alpha (TNFα). We hypothesized that an inflammatory state, characterized by increased soluble TNFα receptor (sTNFR1), mediates sensitivity of the liver to radiation.

Materials/Methods

Plasma samples collected during 3 trials of liver radiation for liver malignancies were assayed for sTNFR1 level via enzyme-linked immunosorbent assay (ELISA). Univariate and multivariate logistic regression and longitudinal models were used to characterize associations between liver toxicity (defined as a ≥2-point increase in Child-Pugh [CP] score within 6 months of radiation treatment) and sTNFR1 levels, ALBI score, biocorrected mean liver dose (MLD), age, and baseline laboratory values.

Results

Samples from 78 patients given liver stereotactic body radiation therapy [SBRT] (92%) or hypofractionated radiation were examined. There was a significant association between liver toxicity and sTNFR1 levels, and higher values were associated with increased toxicity over a range of mean liver doses. When ALBI score and biocorrected dose were included in the model with sTNFR1, baseline ALBI score and change in ALBI (ΔALBI) were significantly associated with toxicity, but sTNFR1 was not. Baseline aminotransferase levels also predicted toxicity but not independently of ALBI score.

Conclusions

Elevated plasma sTNFR1 levels are associated with liver injury after liver radiation, suggesting that elevated inflammatory cytokine activity is a predictor of radiation-induced liver dysfunction. Future studies should determine whether administration of agents that decrease inflammation prior to treatment is warranted.

Radiomics for liver tumours

Current research, especially in oncology, increasingly focuses on the integration of quantitative, multiparametric and functional imaging data. In this fast-growing field of research, radiomics may allow for a more sophisticated analysis of imaging data, far beyond the qualitative evaluation of visible tissue changes. Through use of quantitative imaging data, more tailored and tumour-specific diagnostic work-up and individualized treatment concepts may be applied for oncologic patients in the future. This is of special importance in cross-sectional disciplines such as radiology and radiation oncology, with already high and still further increasing use of imaging data in daily clinical practice. Liver targets are generally treated with stereotactic body radiotherapy (SBRT), allowing for local dose escalation while preserving surrounding normal tissue. With the introduction of online target surveillance with implanted markers, 3D-ultrasound on conventional linacs and hybrid magnetic resonance imaging (MRI)-linear accelerators, individualized adaptive radiotherapy is heading towards realization. The use of big data such as radiomics and the integration of artificial intelligence techniques have the potential to further improve image-based treatment planning and structured follow-up, with outcome/toxicity prediction and immediate detection of (oligo)progression. The scope of current research in this innovative field is to identify and critically discuss possible application forms of radiomics, which is why this review tries to summarize current knowledge about interdisciplinary integration of radiomics in oncologic patients, with a focus on investigations of radiotherapy in patients with liver cancer or oligometastases including multiparametric, quantitative data into (radio)-oncologic workflow from disease diagnosis, treatment planning, delivery and patient follow-up.

Thermal Ablation Versus Stereotactic Body Radiotherapy After Transarterial Chemoembolization for Inoperable Hepatocellular Carcinoma: A Propensity Score-Weighted Analysis

BACKGROUND. Transarterial chemoembolization (TACE) has synergistic properties when combined with ablative therapies for hepatocellular carcinoma (HCC). OBJECTIVE. The purpose of our study was to compare outcomes for inoperable HCC between TACE with percutaneous thermal ablation (TACE-TA) and TACE with stereotactic body radiotherapy (TACE-SBRT) using propensity score-weighted cohorts. METHODS. This retrospective study included 190 patients with a single inoperable HCC treated from 2007 to 2018 by either TACE-SBRT (n = 90) or TACE-TA (n = 100). The primary outcome was overall survival (OS). Secondary outcomes included progression-free survival (PFS) and hepatotoxicity (defined as Child-Pugh score elevation of ≥ 2 within 2-6 months after treatment). Fine-Gray competing risk models with propensity score weighting and transplant as the competing risk factor were used to model OS and PFS. RESULTS. The median follow-up time was 48.2 months. Both OS and PFS were significantly higher for TACE-TA (77% and 76%, respectively, at 2 years) than TACE-SBRT (49% and 50%, respectively, at 2 years) in the propensity score-weighted multivariate model (OS: subdistribution hazard ratio [sHR] = 2.70, p < .001; PFS: sHR = 1.71, p = .02). Treatment-related hepatotoxicity occurred in 9% of patients who underwent TACE-TA versus 27% of those who underwent TACE-SBRT (p = .01). For the subset of patients with Barcelona Clinic Liver Cancer A HCC and Child-Pugh A cirrhosis (TACE-SBRT, n = 36 patients; TACE-TA, n = 55 patients), OS (p = .11) and PFS (p = .19) were not significantly different between the two treatment modalities. CONCLUSION. Compared with TACE-SBRT, TACE-TA showed superior OS and PFS, possibly from its lesser hepatotoxicity. The two strategies did not differ in OS and PFS for patients with the earliest-stage HCC and preserved liver function. CLINICAL IMPACT. Across all patients, TACE-TA may be superior to TACE-SBRT for inoperable HCC.

Combinational Immunotherapy for Hepatocellular Carcinoma: Radiotherapy, Immune Checkpoint Blockade and Beyond

The systemic treatment landscape for advanced hepatocellular carcinoma (HCC) has experienced tremendous paradigm shift towards targeting tumor microenvironment (TME) following recent trials utilizing immune checkpoint blockade (ICB). However, limited success of ICB as monotherapy mandates the evaluation of combination strategies incorporating immunotherapy for improved clinical efficacy. Radiotherapy (RT) is an integral component in treatment of solid cancers, including HCC. Radiation mediates localized tumor killing and TME modification, thereby potentiating the action of ICB. Several preclinical and clinical studies have explored the efficacy of combining RT and ICB in HCC with promising outcomes. Greater efforts are required in discovery and understanding of novel combination strategies to maximize clinical benefit with tolerable adverse effects. This current review provides a comprehensive assessment of RT and ICB in HCC, their respective impact on TME, the rationale for their synergistic combination, as well as the current potential biomarkers available to predict clinical response. We also speculate on novel future strategies to further enhance the efficacy of this combination.

Individualized Adaptive Radiation Therapy Allows for Safe Treatment of Hepatocellular Carcinoma in Patients With Child-Turcotte-Pugh B Liver Disease

PURPOSE

Previous reports of stereotactic body radiation therapy (SBRT) for hepatocellular carcinoma (HCC) suggest unacceptably high rates of toxicity in patients with Child-Turcotte-Pugh (CTP) B liver disease. We hypothesized that an individualized adaptive treatment approach based on midtreatment liver function would maintain good local control while limiting toxicity in this population.

METHODS AND MATERIALS

Patients with CTP-B liver disease and HCC were treated on prospective trials of individualized adaptive SBRT between 2006 and 2018. Patients underwent pre- and midtreatment liver function assessments using indocyanine green. Treatment-related toxicity was defined as a ≥2-point increase in CTP score from pretreatment within 6 months of treatment. In addition, we performed analyses with a longitudinal model to assess changes in CTP score over 12 months after SBRT.

RESULTS

Eighty patients with CTP-B (median tumor size, 2.5 cm) were treated: 37 patients were CTP-B-7, 28 were CTP-B-8, and 15 were CTP-B-9. The median treatment dose was 36 Gy in 3 fractions. One-year local control was 92%. In a multivariate model controlling for tumor size, treatment dose, and baseline CTP score, higher treatment dose was associated with improved freedom from local progression (hazard ratio: 0.97; 95% confidence interval, 0.94-1.00; P = .04). Eighteen patients (24%) had a ≥2-point increase in CTP score within 6 months of SBRT. In a longitudinal model assessing changes in CTP score over 12 months after SBRT, controlling for baseline CTP and tumor size, increasing mean liver dose was associated with larger increases in CTP score (P = .04).

CONCLUSIONS

An individualized adaptive treatment approach allows for acceptable toxicity and effective local control in patients with HCC and CTP-B liver disease. Because increasing dose may increase both local control and toxicity, further work is needed to optimize treatment in patients with compromised liver function.

Ultra-High Dose Rate (FLASH) Radiotherapy: Silver Bullet or Fool's Gold?

Radiotherapy is a cornerstone of both curative and palliative cancer care. However, radiotherapy is severely limited by radiation-induced toxicities. If these toxicities could be reduced, a greater dose of radiation could be given therefore facilitating a better tumor response. Initial pre-clinical studies have shown that irradiation at dose rates far exceeding those currently used in clinical contexts reduce radiation-induced toxicities whilst maintaining an equivalent tumor response. This is known as the FLASH effect. To date, a single patient has been subjected to FLASH radiotherapy for the treatment of subcutaneous T-cell lymphoma resulting in complete response and minimal toxicities. The mechanism responsible for reduced tissue toxicity following FLASH radiotherapy is yet to be elucidated, but the most prominent hypothesis so far proposed is that acute oxygen depletion occurs within the irradiated tissue. This review examines the tissue response to FLASH radiotherapy, critically evaluates the evidence supporting hypotheses surrounding the biological basis of the FLASH effect, and considers the potential for FLASH radiotherapy to be translated into clinical contexts.

Non-Invasive Targeted Hepatic Irradiation and SPECT/CT Functional Imaging to Study Radiation-Induced Liver Damage in Small Animal Models

Radiation therapy (RT) has traditionally not been widely used in the management of hepatic malignancies for fear of toxicity in the form of radiation-induced liver disease (RILD). Pre-clinical hepatic irradiation models can provide clinicians with better understanding of the radiation tolerance of the liver, which in turn may lead to the development of more effective cancer treatments. Previous models of hepatic irradiation are limited by either invasive laparotomy procedures, or the need to irradiate the whole or large parts of the liver using external skin markers. In the setting of modern-day radiation oncology, a truly translational animal model would require the ability to deliver RT to specific parts of the liver, through non-invasive image guidance methods. To this end, we developed a targeted hepatic irradiation model on the Small Animal Radiation Research Platform (SARRP) using contrast-enhanced cone-beam computed tomography image guidance. Using this model, we showed evidence of the early development of region-specific RILD through functional single photon emission computed tomography (SPECT) imaging.

Stereotactic body radio therapy for inoperable large hepatocellular cancers: results from a clinical audit

OBJECTIVES

To evaluate the outcomes of stereotactic radiotherapy (SBRT) in the treatment of inoperable hepatocellular carcinomas (HCC) that are unsuitable for, or refractory to other liver-directed therapies.

METHODS

Between March 2015 and June 2018, patients with primary HCCs refractory to or unsuitable for treatment with other liver-directed therapies were treated with SBRT. Patients of Child status A5-B7 and with normal liver reserve ≥ 700 cc were preferred. Local control (LC), overall survival (OS), progression free survival (PFS) and effect of prognostic factors were analysed.

RESULTS

21 patients with inoperable HCCs were treated. The median tumour diameter was 9.6 cm (5-21) and median tumour volume was 350 cc (32.9 - 2541). The median SBRT dose prescription was 42 Gy/6 fractions (25 - 54 Gy/6#). The 1- and 2-year LC rate was 88 and 43 % respectively. Overall rate of > grade III toxicity was 14 %. Patients with Child A5 liver function had a better median OS than A6 and B7 patients [21 vs 11 vs 8 months]. Also, tumours with GTV < 350 cc volumes had a better OS compared to GTV of greater than 350 cc [24 months vs 8 months, p value = 0.004].

CONCLUSIONS

This study showed that SBRT can be used safely and effectively to treat inoperable HCCs with or without prior loco-regional therapies, resulting in good local control and survival with acceptable toxicity.

ADVANCES IN KNOWLEDGE

Use of SBRT in inoperable HCC is safe and effective.

Stereotactic body radiation therapy in patients with hepatocellular carcinoma: A mini-review

Stereotactic body radiation therapy (SBRT) is an emerging treatment for hepatocellular carcinoma. This technique results in excellent local control rates with favorable toxicity profile despite being predominantly used in heavily pretreated patients or those unsuitable for other local therapies. SBRT may be used as a sole treatment or in combination with other local therapies as well as a bridging strategy for patient awaiting liver transplants. This brief review describes current practice of SBRT with respect to radiation technique, patient selection and treatment concepts. It summarizes available evidence from retro- and prospective studies evaluating SBRT alone, SBRT in combination with other treatments and SBRT compared to other local treatment approaches.

Treatment Outcome after Fractionated Conformal Radiotherapy for Hepatocellular Carcinoma in Patients with Child-Pugh Classification B in Korea (KROG 16-05)

Purpose

There is limited data on radiotherapy (RT) for hepatocellular carcinoma (HCC) in patients with Child-Pugh classification B (CP-B). This study aimed to evaluate the treatment outcomes of fractionated conformal RT in HCC patients with CP-B.

Materials and Methods

We retrospectively reviewed the data of HCC patients with CP-B treated with RT between 2009 and 2014 at 13 institutions in Korea. HCC was diagnosed by the Korea guideline of 2009, and modern RT techniques were applied. Fraction size was ≤ 5 Gy and the biologically effective dose (BED) ≥ 40 Gy₁₀ (α/β = 10 Gy). A total of 184 patients were included in this study.

Results

Initial CP score was seven in 62.0% of patients, eight in 31.0%, and nine in 7.0%. Portal vein tumor thrombosis was present in 66.3% of patients. The BED ranged from 40.4 to 89.6 Gy₁₀ (median, 56.0 Gy₁₀). After RT completion, 48.4% of patients underwent additional treatment. The median overall survival (OS) was 9.4 months. The local progression-free survival and OS rates at 1 year were 58.9% and 39.8%, respectively. In the multivariate analysis, non-classic radiation-induced liver disease (RILD) (p < 0.001) and additional treatment (p < 0.001) were the most significant prognostic factors of OS. Among 132 evaluable patients without progressive disease, 19.7% experienced non-classic RILD. Normal liver volume was the most predictive dosimetric parameter of non-classic RILD.

Conclusion

Fractionated conformal RT showed favorable OS with a moderate risk non-classic RILD. The individual radiotherapy for CP-B could be cautiously applied weighing the survival benefits and the RILD risks.

In-vivo treatment accuracy analysis of active motion-compensated liver SBRT through registration of plan dose to post-therapeutic MRI-morphologic alterations

BACKGROUND/PURPOSE

In-vivo-accuracy analysis (IVA) of dose-delivery with active motion-management (gating/tracking) was performed based on registration of post-radiotherapeutic MRI-morphologic-alterations (MMA) to the corresponding dose-distributions of gantry-based/robotic SBRT-plans.

METHODS

Forty targets in two patient cohorts were evaluated: (1) gantry-based SBRT (deep-inspiratory breath-hold-gating; GS) and (2) robotic SBRT (online fiducial-tracking; RS). The planning-CT was deformably registered to the first post-treatment contrast-enhanced T1-weighted MRI. An isodose-structure cropped to the liver (ISL) and corresponding to the contoured MMA was created. Structure and statistical analysis regarding volumes, surface-distance, conformity metrics and center-of-mass-differences (CoMD) was performed.

RESULTS

Liver volume-reduction was -43.1 ± 148.2 cc post-RS and -55.8 ± 174.3 cc post-GS. The mean surface-distance between MMA and ISL was 2.3 ± 0.8 mm (RS) and 2.8 ± 1.1 mm (GS). ISL and MMA volumes diverged by 5.1 ± 23.3 cc (RS) and 16.5 ± 34.1 cc (GS); the median conformity index of both structures was 0.83 (RS) and 0.80 (GS). The average relative directional errors were ≤0.7 mm (RS) and ≤0.3 mm (GS); the median absolute 3D-CoMD was 3.8 mm (RS) and 4.2 mm (GS) without statistically significant differences between the two techniques. Factors influencing the IVA included GTV and PTV (p = 0.041 and p = 0.020). Four local relapses occurred without correlation to IVA.

CONCLUSIONS

For the first time a method for IVA was presented, which can serve as a benchmarking-tool for other treatment techniques. Both techniques have shown median deviations <5 mm of planned dose and MMA. However, IVA also revealed treatments with errors ≥5 mm, suggesting a necessity for patient-specific safety-margins. Nevertheless, the treatment accuracy of well-performed active motion-compensated liver SBRT seems not to be a driving factor for local treatment failure.

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

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.

Comparison of three-dimensional conformal radiotherapy and hepatic resection in hepatocellular carcinoma with portal vein tumor thrombus

OBJECTIVE

This study aimed to evaluate the safety and efficacy of three-dimensional conformal radiotherapy (3D-CRT) and hepatic resection for patients with hepatocellular carcinoma (HCC) involving portal vein tumor thrombus (PVTT).

METHODS

We retrospectively analyzed 323 HCC patients involving PVTT. Among them, 134 patients underwent 3D-CRT, while 189 controls treated with hepatic resection (HR). Survival rate and prognostic analysis were performed using Kaplan-Meier method and Cox regression analyses.

RESULTS

The 1-, 2-, and 3-year overall survival (OS) of RT group and HR group was 54% vs 62%, 33% vs 47%, and 18% vs 43%, respectively (P = 0.003). In the subgroup of PVTT type analysis, the 1-, 2-, and 3-year OS in RT group was 65%, 39%, and 19%, respectively, while that in HR group was 83%, 53%, and 42%, respectively, in type I PVTT (P < 0.001). The 1-, 2-, and 3-year OS in RT group was 52%, 35%, and 11%, while that in HR group was 55%, 42%, and 25%, respectively, in type II PVTT (P = 0.612). In type III PVTT, the 1-, 2-, and 3-year OS in RT group was 16%, 3%, and 0%, respectively, while that in HR group was 11%, 0%, and 0%, respectively (P = 0.041). Multivariate analysis revealed that tumor size ≥10 cm, Child-Pugh class B, and type III PVTT are independent predictors of poor prognosis in HCC with PVTT.

CONCLUSION

3D-CRT appears to be an effective treatment for patients with HCC involving type II/III PVTT.