Stereotactic body radiation therapy for early hepatocellular carcinoma: a retrospective analysis of the South Australian experience

Refining stereotactic body radiation therapy as a bridge to transplantation for hepatocellular carcinoma: An institutional experience

BACKGROUND

Stereotactic body radiotherapy (SBRT) has been established as a safe and effective treatment for hepatocellular carcinoma (HCC). Currently, there are no consensus guidelines to advise optimal patient selection and radiotherapy planning parameters to minimise the risk of surgical and medical complications after liver transplant (LT) in patients who have had prior SBRT for HCC, whilst optimising treatment benefit.

METHODS

We performed a retrospective analysis of all adult patients who received liver SBRT as a bridge to LT at a tertiary institution between 2017 and 2019.

RESULTS

Nine patients received SBRT as bridging therapy to LT. HCC location varied from peripheral to central/hilar regions and HCC diameter was 13-54 mm. Median time between SBRT and LT was 141 days (range 27-461 days). Median operating time was 360 min (range 270-480 min). Four patients (44%) had visible SBRT reaction or fibrosis at the time of LT. SBRT reaction resulted in clinical impact in one patient (11%) only, where vascular clamping of the IVC was required for 10 min.

CONCLUSION

SBRT is a safe and effective treatment for HCC enabling patients to remain within LT criteria, even for lesions not amenable to other more conventional bridging therapies. We describe a preliminary decision pathway to guide the optimal use of SBRT as a bridge to LT developed in our institution.

Utility of Real-time CT/MRI-US Automatic Fusion System Based on Vascular Matching in Percutaneous Radiofrequency Ablation for Hepatocellular Carcinomas: A Prospective Study

PURPOSE

To prospectively evaluate the technical success rate of real-time computed tomography/magnetic resonance imaging and ultrasound (CT/MRI-US) automatic fusion system and the long-term therapeutic efficacy of radiofrequency ablation (RFA) guided by automatic fusion in hepatocellular carcinoma (HCC) patients.

MATERIALS AND METHODS

139 patients with 151 HCCs were prospectively enrolled for RFA guided by an automatic CT/MRI-US fusion system (PercuNav system, Philips, the Netherlands). Automatic fusion imaging, based on vascular segmentation and registration, was performed by sonographic sweeping at the intercostal plane. The fusion quality, tumor localization confidence and technical feasibility were recorded before and after fusion using a scoring system. Technical success rate of the RFA procedure and local tumor progression (LTP) were assessed during follow-up. Analysis of technical success and LTP was performed using generalized estimating equations and Cox proportional hazard regression analysis.

RESULTS

The success rate of the fusion system was 82.7% (115/139) per patient. The mean sonographic scan time for fusion was 154.4 ± 108.4 s. In patients with successful fusion, the score indicating tumor localization confidence (2.2 ± 0.8 vs. 2.7 ± 0.9) and technical feasibility (2.6 ± 0.8 vs. 3.4 ± 0.7) increased after fusion (p < 0.001). The technical success rate of the RFA procedure was 96.8% (120/124) per tumor in patients with successful fusion, including poorly localized tumors. LTP rates were 8.6%, 12.2% and 15.2% at 1, 2 and 3 years.

CONCLUSION

The CT/MRI-US automatic fusion system showed a high success rate for image registration and facilitated better feasibility and a high technical success rate of RFA in HCCs, even with poor localization on US.

LEVEL OF EVIDENCE

Level 3b, Nonrandomized prospective study.

A study of the interplay effect for VMAT SBRT using a four-axes motion phantom

Purpose

To assess the accuracy of volumetric modulated arc therapy (VMAT) stereotactic body radiation therapy (SBRT) when treating moving targets (such as lung or liver lesions), focusing on the impact of the interplay effect in the event of complex breathing motion and when a gating window is used.

Methods

A dedicated programmable motion platform was implemented. This platform can carry large quality assurance (QA) phantoms and achieve complex three‐dimensional (3D) motion. Volumetric modulated arc therapy SBRT plans were delivered with TrueBeam linac to this moving setup and the measured dose was compared to the computed one. Several parameters were assessed such as breathing period, dose rate, dose prescription, shape of the breathing pattern, the use of a planning target volume (PTV) margin, and the use of a gating window.

Results

Loss of dose coverage (D95%) was acceptable in most situations. The doses received by 95% of the CTV, D95% ( CTVm) ranged from 94 to 101% (mean 98%) and the doses received by 2% of the CTV D2% ( CTVm) ranged from 94% to 110% of the prescribed dose. A visible interplay effect was observed when no margin was used or when the number of breathing cycles during the treatment delivery was lower than 20.

Conclusions

In our clinical context, treating lung and liver lesions using VMAT SBRT is reasonable. The interplay effect was moderated and acceptable in all simulated situations.

Factors affecting target motion in stereotactic body radiotherapy of liver cancer using CyberKnife

INTRODUCTION

In stereotactic body radiation therapy (SBRT) of solitary liver cancer, organ motion due to respiration is an important factor in the definition of planning target volume (PTV). This study evaluated the potential associations of target motion with gross tumour volume (GTV) size, tumour location, Child-Pugh score and intra-fraction treatment time in SBRT of liver cancer treated by CyberKnife.

METHODS

Translational motion data of 145 liver cancer patients, who were previously treated by CyberKnife with free breathing under tumour tracking, were recorded in the log files of the motion tracking system and analysed. The factors including target location based on liver segments, Child-Pugh score which was an indication of liver cirrhosis, GTV size and intra-fraction treatment time were recorded and their associations with the magnitude of target movement were evaluated.

RESULTS

Target location demonstrated significant association with the translational target motion in the supero-inferior (SI) and left-right (LR) directions but less in antero-posterior (AP) direction. Tumours located at the peripheral segments were more affected than the central segments. Child-Pugh score and GTV size were not significantly associated with target motion in any direction. Longer intra-fraction treatment time generally increased target motion in the SI and LR directions.

CONCLUSION

In SBRT of liver cancer, the target motions in SI and LR directions were correlated with the location of target and treatment time, but not with Child-Pugh score and GTV size. These results should assist in deciding the GTV-PTV margin in SBRT treatment planning for solitary liver cancer.