Stereotactic radiotherapy of primary liver cancer and hepatic metastases

Clinical and Dosimetric Impact of 2D kV Motion Monitoring and Intervention in Liver Stereotactic Body Radiation Therapy

Purpose

Positional errors resulting from motion are a principal challenge across all disease sites in radiation therapy. This is particularly pertinent when treating lesions in the liver with stereotactic body radiation therapy (SBRT). To achieve dose escalation and margin reduction for liver SBRT, kV real-time imaging interventions may serve as a potential solution. In this study, we report results of a retrospective cohort of liver patients treated using real-time 2D kV-image guidance SBRT with emphasis on the impact of (1) clinical workflow, (2) treatment accuracy, and (3) tumor dose.

Methods and Materials

Data from 33 patients treated with 41 courses of liver SBRT were analyzed. During treatment, planar kV images orthogonal to the treatment beam were acquired to determine treatment interventions, namely treatment pauses (ie, adequacy of gating thresholds) or treatment shifts. Patients were shifted if internal markers were >3 mm, corresponding to the PTV margin used, from the expected reference condition. The frequency, duration, and nature of treatment interventions (ie, pause vs shift) were recorded, and the dosimetric impact associated with treatment shifts was estimated using a machine learning dosimetric model.

Results

Of all fractions delivered, 39% required intervention, which took on average 1.9 ± 1.6 minutes and occurred more frequently in treatments lasting longer than 7 minutes. The median realignment shift was 5.7 mm in size, and the effect of these shifts on minimum tumor dose in simulated clinical scenarios ranged from 0% to 50% of prescription dose per fraction.

Conclusion

Real-time kV-based imaging interventions for liver SBRT minimally affect clinical workflow and dosimetrically benefit patients. This potential solution for addressing positional errors from motion addresses concerns about target accuracy and may enable safe dose escalation and margin reduction in the context of liver SBRT.

Nanodrugs Reprogram Cancer-Associated Fibroblasts and Normalize Tumor Vasculatures for Sequentially Enhancing Photodynamic Therapy of Hepatocellular Carcinoma

Background

The failure of cancer photodynamic therapy (PDT) is largely ascribed to excessive stroma and defective vasculatures that restrain the photosensitizer permeation and the oxygen perfusion in tumors.

Method and Results

In this study, a nanodrug that integrated the cancer-associated fibroblast (CAF) regulation with tumor vessel normalization was tailored to sequentially sensitize PDT. The nanodrug exhibited high targeting towards CAFs and efficiently reversed the activated CAFs into quiescence, thus decreasing collagen deposition in the tumor microenvironment (TME), which overcame the protective physical barrier. Furthermore, the nanodrug regulated vascular endothelial cells and restored the tumor vasculatures, thereby improving vascular permeability. Based on the combined effects of reprogramming the TME, the nanodrug improved tumor accumulation of photosensitizers and alleviated hypoxia in the TME, which facilitated the subsequent PDT. Importantly, the nanodrug regulated the immunosuppressive TME by favoring the infiltration of immunostimulatory cells over immunosuppressive cells, which potentiated the PDT-induced immune response.

Conclusion

Our work demonstrates a sequential treatment strategy in which the combination of the CAF regulation and tumor vasculature normalization, followed by PDT, could be a promising modality for sensitizing tumor to PDT.

Real-world effectiveness and safety of stereotactic body radiotherapy for liver metastases with different respiratory motion management techniques

PURPOSE

Stereotactic body radiotherapy (SBRT) has been firmly established as a treatment choice for patients with oligometastases, as it has demonstrated both safety and efficacy by consistently achieving high rates of local control. Moreover, it offers potential survival benefits for carefully selected patients in real-world clinical settings.

METHODS

Between January 2008 and May 2020, a total of 149 patients (with 414 liver metastases) received treatment. The Active Breathing Coordinator device was used for 68 patients, while respiratory gating was used for 65 and abdominal compression was used for 16 patients. The most common histological finding was colorectal adenocarcinoma, with 37.6% of patients having three or more metastases, and 18% having two metastases. The prescribed dose ranged from 36 to 60 Gy, delivered in 3-5 fractions.

RESULTS

Local control rates at 2 and 3 years were 76.1% and 61.2%, respectively, with no instances of local recurrence after 3 years. Factors negatively impacting local control included colorectal histology, lower prescribed dose, and the occurrence of new liver metastases. The median overall survival from SBRT was 32 months, with the presence of metastases outside the liver and the development of new liver metastases after SBRT affecting survival. The median disease-free survival was 10 months. No substantial differences in both local control and survival were observed between the respiratory motion control techniques employed. Treatment tolerance was excellent, with only one patient experiencing acute grade IV thrombocytopenia and two patients suffering from ≥ grade II chronic toxicity.

CONCLUSION

For radical management of single or multiple liver metastases, SBRT is an effective and well-tolerated treatment option. Regardless of the technology employed, experienced physicians can achieve similarly positive outcomes. However, additional studies are required to elucidate prognostic factors that can facilitate improved patient selection.

American Radium Society Appropriate Use Criteria for the use of liver-directed therapies for nonsurgical management of liver metastases: Systematic review and guidelines

The liver is a common site of cancer metastases. Systemic therapy is widely accepted as the standard treatment for liver metastases (LM), although select patients with liver oligometastases may be candidates for potentially curative liver resection. Recent data support the role of nonsurgical local therapies such as ablation, external beam radiotherapy, embolization, and hepatic artery infusion therapy for management of LM. Additionally, for patients with advanced, symptomatic LM, local therapies may provide palliative benefit. The American Radium Society gastrointestinal expert panel, including members representing radiation oncology, interventional radiology, surgical oncology, and medical oncology, performed a systemic review and developed Appropriate Use Criteria for the use of nonsurgical local therapies for LM. Preferred Reporting Items for Systematic reviews and Meta-Analyses methodology was used. These studies were used to inform the expert panel, which then rated the appropriateness of various treatments in seven representative clinical scenarios through a well-established consensus methodology (modified Delphi). A summary of recommendations is outlined to guide practitioners on the use of nonsurgical local therapies for patients with LM.

Metabolic factors associated with the prognosis of oligometastatic patients treated with stereotactic body radiotherapy

Over the past two decades, it has been established that cancer patients with oligometastases, i.e., only a few detectable metastases confined to one or a few organs, may benefit from an aggressive local treatment approach such as the application of high-precision stereotactic body radiotherapy (SBRT). Specifically, some studies have indicated that achieving long-term local tumor control of oligometastases is associated with prolonged overall survival. This motivates investigations into which factors may modify the dose-response relationship of SBRT by making metastases more or less radioresistant. One such factor relates to the uptake of the positron emission tomography tracer 2-deoxy-2-[18F]fluoro-D-glucose (FDG) which reflects the extent of tumor cell glycolysis or the Warburg effect, respectively. Here we review the biological mechanisms how the Warburg effect drives tumor cell radioresistance and metastasis and draw connections to clinical studies reporting associations between high FDG uptake and worse clinical outcomes after SBRT for oligometastases. We further review the evidence for distinct metabolic phenotypes of metastases preferentially seeding to specific organs and their possible translation into distinct radioresistance. Finally, evidence that obesity and hyperglycemia also affect outcomes after SBRT will be presented. While delivered dose is the main determinant of a high local tumor control probability, there might be clinical scenarios when metabolic targeting could make the difference between achieving local control or not, for example when doses have to be compromised in order to spare neighboring high-risk organs, or when tumors are expected to be highly therapy-resistant due to heavy pretreatment such as chemotherapy and/or radiotherapy.

Unresectable Intermediate-Size (3-5 cm) Colorectal Liver Metastases: Stereotactic Ablative Body Radiotherapy Versus Microwave Ablation (COLLISION-XL): Protocol of a Phase II/III Multicentre Randomized Controlled Trial

BACKGROUND

Although microwave ablation (MWA) has a low complication rate and good efficacy for small-size (≤ 3 cm) colorectal liver metastases (CRLM), local control decreases with increasing size. Stereotactic body radiotherapy (SBRT) is gaining interest as a potential means to treat intermediate-size CRLM and might be less susceptible to increasing volume. The objective of this study is to compare the efficacy of MWA to SBRT in patients with unresectable, intermediate-size (3-5 cm) CRLM.

METHODS

In this two-arm, multicentre phase II/ III randomized controlled trial, 68 patients with 1-3 unresectable, intermediate-size CRLM suitable for both MWA and SBRT, will be included. Patients will be treated with MWA or SBRT as randomised. The Primary endpoint is local tumour progression-free survival (LTPFS) at 1 year (intention-to-treat analysis). Main secondary endpoints are overall survival, overall and distant progression-free survival (DPFS), local control (LC) and procedural morbidity and mortality and assessment of pain and quality of life.

DISCUSSION

Current guidelines lack clear recommendations for the local treatment of liver only intermediate-size, unresectable CRLM and studies comparing curative intent SBRT and thermal ablation are scarce. Although safety and feasibility to eradicate tumours ≤ 5 cm have been established, both techniques suffer from lower LTPFS and LC rates for larger-size tumours. For the treatment of unresectable intermediate-size CRLM clinical equipoise has been reached. We have designed a two-armed phase II/ III randomized controlled trial directly comparing SBRT to MWA for unresectable CRLM 3-5 cm.

LEVEL OF EVIDENCE

Level 1, phase II/ III Randomized controlled trial.

TRIAL REGISTRATION

NCT04081168, September 9th 2019.

Adaptive fractionation at the MR-linac

Objective. Fractionated radiotherapy typically delivers the same dose in each fraction. Adaptive fractionation (AF) is an approach to exploit inter-fraction motion by increasing the dose on days when the distance of tumor and dose-limiting organs at risk (OAR) is large and decreasing the dose on unfavorable days. We develop an AF algorithm and evaluate the concept for patients with abdominal tumors previously treated at the MR-linac in 5 fractions.Approach. Given daily adapted treatment plans, inter-fractional changes are quantified by sparing factorsδ_tdefined as the OAR-to-tumor dose ratio. The key problem of AF is to decide on the dose to deliver in fractiont, givenδ_tand the dose delivered in previous fractions, but not knowing futureδ_ts. Optimal doses that maximize the expected biologically effective dose in the tumor (BED₁₀) while staying below a maximum OAR BED₃constraint are computed using dynamic programming, assuming a normal distribution overδwith mean and variance estimated from previously observed patient-specificδ_ts. The algorithm is evaluated for 16 MR-linac patients in whom tumor dose was compromised due to proximity of bowel, stomach, or duodenum.Main Results. In 14 out of the 16 patients, AF increased the tumor BED₁₀compared to the reference treatment that delivers the same OAR dose in each fraction. However, in 11 of these 14 patients, the increase in BED₁₀was below 1 Gy. Two patients with large sparing factor variation had a benefit of more than 10 Gy BED₁₀increase. For one patient, AF led to a 5 Gy BED₁₀decrease due to an unfavorable order of sparing factors.Significance. On average, AF provided only a small increase in tumor BED. However, AF may yield substantial benefits for individual patients with large variations in the geometry.

Potential benefits of using radioactive ion beams for range margin reduction in carbon ion therapy

Sharp dose gradients and high biological effectiveness make ions such as ¹²C an ideal tool to treat deep-seated tumors, however, at the same time, sensitive to errors in the range prediction. Tumor safety margins mitigate these uncertainties, but during the irradiation they lead to unavoidable damage to the surrounding healthy tissue. To fully exploit the Bragg peak benefits, a large effort is put into establishing precise range verification methods. Despite positron emission tomography being widely in use for this purpose in ¹²C therapy, the low count rates, biological washout, and broad activity distribution still limit its precision. Instead, radioactive beams used directly for treatment would yield an improved signal and a closer match with the dose fall-off, potentially enabling precise in vivo beam range monitoring. We have performed a treatment planning study to estimate the possible impact of the reduced range uncertainties, enabled by radioactive ¹¹C ions treatments, on sparing critical organs in tumor proximity. Compared to ¹²C treatments, (i) annihilation maps for ¹¹C ions can reflect sub- millimeter shifts in dose distributions in the patient, (ii) outcomes of treatment planning with ¹¹C significantly improve and (iii) less severe toxicities for serial and parallel critical organs can be expected.

Radiotherapy respiratory motion management in hepatobiliary and pancreatic malignancies: a systematic review of patient factors influencing effectiveness of motion reduction with abdominal compression

BACKGROUND

The effectiveness of abdominal compression for motion management in hepatobiliary-pancreatic (HPB) radiotherapy has not been systematically evaluated.

METHODS & MATERIALS

A systematic review was carried out using PubMed/Medline, Cochrane Library, Web of Science, and CINAHL databases up to 1 July 2021. No date restrictions were applied. Additional searches were carried out using the University of Manchester digital library, Google Scholar and of retrieved papers' reference lists. Studies conducted evaluating respiratory motion utilising imaging with and without abdominal compression in the same patients available in English were included. Studies conducted in healthy volunteers or majority non-HPB sites, not providing descriptive motion statistics or patient characteristics before and after compression in the same patients or published without peer-review were excluded. A narrative synthesis was employed by tabulating retrieved studies and organising chronologically by abdominal compression device type to help identify patterns in the evidence.

RESULTS

The inclusion criteria were met by 6 studies with a total of 152 patients. Designs were a mix of retrospective and prospective quantitative designs with chronological, non-randomised recruitment. Abdominal compression reduced craniocaudal respiratory motion in the majority of patients, although in four studies there were increases seen in at least one direction. The influence of patient comorbidities on effectiveness of compression, and/or comfort with compression was not evaluated in any study.

CONCLUSION

Abdominal compression may not be appropriate for all patients, and benefit should be weighed with potential increase in motion or discomfort in patients with small initial motion (<5 mm). Patient factors including male sex, and high body mass index (BMI) were found to impact the effectiveness of compression, however with limited evidence. High-quality studies are warranted to fully assess the clinical impact of abdominal compression on treatment outcomes and toxicity prospective in comparison to other motion management strategies.

Stereotactic radiotherapy for liver oligometastases

The liver is the first metastatic site in 15–25% of colorectal cancer patients and one of the first metastatic sites for lung and breast cancer patients.

A computed tomography (CT ) scan with contrast medium is a standard procedure for assessing liver lesions but magnetic resonance imaging (MRI) characterizes small lesions better thanks to its high soft-tissue contrast. Positron emission tomography with computed tomography (PET-CT ) plays a complementary role in the diagnosis of liver metastases. Triphasic (arterial, venous and time-delayed) acquisition of contrast-medium CT images is the first step in treatment planning. Since the liver exhibits a relatively wide mobility due to respiratory movements and bowel filling, appropriate techniques are needed for target identification and motion management. Contouring requires precise recognition of target lesion edges. Information from contrast MRI and/or PET-CT is crucial as they best visualize metastatic disease in the parenchyma. Even though different fractionation schedules were reported, doses and fractionation schedules for liver stereotactic radiotherapy (SRT ) have not yet been established. The best local control rates were obtained with BED₁₀ values over 100 Gy. Local control rates from most retrospective studies, which were limited by short follow-ups and included different primary tumors with intrinsic heterogeneity, ranged from 60% to 90% at 1 and 2 years. The most common SRT-related toxicities are increases in liver enzymes, hyperbilirubinemia and hypoalbuminemia. Overall, late toxicity is mild even in long-term follow-ups.

Comprehensive Analysis of CDK1-Associated ceRNA Network Revealing the Key Pathways LINC00460/LINC00525-Hsa-Mir-338-FAM111/ZWINT as Prognostic Biomarkers in Lung Adenocarcinoma Combined with Experiments

Lung adenocarcinoma (LUAD) is the leading cause of cancer deaths worldwide, and effective biomarkers are still lacking for early detection and prognosis prediction. Here, based on gene expression profiles of LUAD patients from The Cancer Genome Atlas (TCGA), 806 long non-coding RNAs (lncRNAs), 122 microRNAs (miRNAs) and 1269 mRNAs associated with CDK1 were identified. The regulatory axis of LINC00460/LINC00525-hsa-mir-338-FAM111B/ZWINT was determined according to the correlation between gene expression and patient prognosis. The abnormal up-regulation of FAM111B/ZWINT in LUAD was related to hypomethylation. Furthermore, immune infiltration analysis suggested FAM111B/ZWINT could affect the development and prognosis of cancer by regulating the LUAD immune microenvironment. EMT feature analysis suggested that FAM111B/ZWINT promoted tumor spread through the EMT process. Functional analysis showed FAM111B/ZWINT was involved in cell cycle events such as DNA replication and chromosome separation. We analyzed the HERB and GSCALite databases to identify potential target medicines that may play a role in the treatment of LUAD. Finally, the expression of LINC00460/LINC00525-hsa-mir-338-FAM111B/ZWINT axis was verified in LUAD cells by RT-qPCR, and these results were consistent with bioinformatics analysis. Overall, we constructed a CDK1-related ceRNA network and revealed the LINC00460/LINC00525-hsa-mir-338-FAM111/ZWINT pathways as potential diagnostic biomarkers or therapeutic targets of LUAD.

The Role of Ablative Radiotherapy to Liver Oligometastases from Colorectal Cancer

Purpose of Review

This review describes recent data supporting locoregional ablative radiation in the treatment of oligometastatic colorectal cancer liver metastases.

Recent Findings

Stereotactic body radiotherapy (SBRT) demonstrates high rates of local control in colorectal cancer liver metastases when a biologically equivalent dose of > 100 Gy is delivered. Future innovations to improve the efficacy of SBRT include MRI-guided radiotherapy (MRgRT) to enhance target accuracy, systemic immune activation to treat extrahepatic disease, and genomic customization. Selective internal radiotherapy (SIRT) with y-90 is an intra-arterial therapy that delivers high doses to liver metastases internally which has shown to increase liver disease control in phase 3 trials. Advancements in transarterial radioembolization (TARE) dosimetry could improve local control and decrease toxicity.

Summary

SBRT and SIRT are both promising options in treating unresectable metastatic colorectal cancer liver metastases. Identification of oligometastatic patients who receive long-term disease control from either therapy is essential. Future advancements focusing on improving radiation design and customization could further improve efficacy and toxicity.

Direct visualization and correlation of liver stereotactic body radiation therapy treatment delivery accuracy with interfractional motion

This study used the visualization of hypo‐intense regions on liver‐specific MRI to directly quantify stereotactic body radiation therapy (SBRT) spatial delivery accuracy. Additionally, the interfractional motion of the liver region was determined and compared with the MRI‐based evaluation of liver SBRT spatial treatment delivery accuracy. Primovist^®‐enhanced MRI scans were acquired from 17 patients, 8–12 weeks following the completion of liver SBRT treatment. Direct visualization of radiation‐induced focal liver reaction in the form of hypo‐intensity was determined. The auto‐delineation approach was used to localize these regions, and center‐of‐mass (COM) discrepancy was quantified between the MRI hypo‐intensity and the CT‐based treatment plan. To assess the interfractional motion of the liver region, a planning CT was registered to a Cone Beam CT obtained before each treatment fraction. The interfractional motion assessed from this approach was then compared against the localized hypo‐intense MRI regions. The mean ± SD COM discrepancy was 1.4 ± 1.3 mm in the left‐right direction, 2.6 ± 1.8 mm in an anteroposterior direction, and 1.9 ± 2.6 mm in the craniocaudal direction. A high correlation was observed between interfractional motion of visualized hypo‐intensity and interfractional motion of planning treatment volume (PTV); the quantified Pearson correlation coefficient was 0.96. The lack of correlation was observed between Primovist^® MRI‐based spatial accuracy and interfractional motion of the liver, where Pearson correlation coefficients ranged from −0.01 to −0.26. The highest random and systematic errors quantified from interfractional motion were in the craniocaudal direction. This work demonstrates a novel framework for the direct evaluation of liver SBRT spatial delivery accuracy.

Benefit of replanning in MR-guided online adaptive radiation therapy in the treatment of liver metastasis

PURPOSE

To assess the effects of daily adaptive MR-guided replanning in stereotactic body radiation therapy (SBRT) of liver metastases based on a patient individual longitudinal dosimetric analysis.

METHODS

Fifteen patients assigned to SBRT for oligometastatic liver metastases underwent daily MR-guided target localization and on-table treatment plan re-optimization. Gross tumor volume (GTV) and organs at risk (OARs) were adapted to the anatomy-of-the-day. A reoptimized plan (RP) and a rigidly shifted baseline plan (sBP) without re-optimization were generated for each fraction. After extraction of DVH parameters for GTV, planning target volume (PTV), and OARs (stomach, duodenum, bowel, liver, heart) plans were compared on a per-patient basis.

RESULTS

Median pre-treatment GTV and PTV were 14.9 cc (interquartile range (IQR): 7.7-32.9) and 62.7 cc (IQR: 42.4-105.5) respectively. SBRT with RP improved PTV coverage (V100%) for 47/75 of the fractions and reduced doses to the most proximal OARs (D1cc, Dmean) in 33/75 fractions compared to sBP. RP significantly improved PTV coverage (V100%) for metastases within close proximity to an OAR by 4.0% (≤ 0.2 cm distance from the edge of the PTV to the edge of the OAR; n = 7; p = 0.01), but only by 0.2% for metastases farther away from OAR (> 2 cm distance; n = 7; p = 0.37). No acute grade 3 treatment-related toxicities were observed.

CONCLUSIONS

MR-guided online replanning SBRT improved target coverage and OAR sparing for liver metastases with a distance from the edge of the PTV to the nearest luminal OAR < 2 cm. Only marginal improvements in target coverage were observed for target distant to critical OARs, indicating that these patients do not benefit from daily adaptive replanning.

Carbon-ion Radiotherapy for Colorectal Cancer

Heavy-ion radiotherapy (RT) is a kind of particle RT, and carbon-ion beam constitutes the primary delivery method of heavy-ion RT. Unlike the conventional photon modalities, particle RT, in particular carbon-ion radiotherapy (CIRT), offers unique physical and biological advantages. Particle therapy allows for substantial dose delivery to tumors with minimal surrounding tissue damage. In addition, CIRT in particular possesses biological advantages such as inducing increased double-strand breaks in DNA structures, causing irreversible cell damage independently of cell cycle or oxygenation, more so than proton or photon. It can be expected that CIRT is effective on radioresistant cancers such as colorectal cancers (CRCs). We introduced the results of CIRT for local recurrent rectal cancer, lung metastasis, liver metastasis, and lymph node metastasis.

Long-Term Results of a Phase 1 Dose-Escalation Trial and Subsequent Institutional Experience of Single-Fraction Stereotactic Ablative Radiation Therapy for Liver Metastases

PURPOSE

We report long-term outcomes from our phase 1 dose-escalation study to determine the maximum tolerated dose of single-fraction liver SABR pooled with our subsequent single institutional experience with patients treated postprotocol at the highest dose level (40 Gy) established from the phase 1 study.

METHODS AND MATERIALS

Patients with liver metastases from solid tumors located outside of the central liver zone were treated with single-fraction SABR on a phase 1 dose escalation trial. At least 700 cc of normal liver had to receive <9.1 Gy. Seven patients with 10 liver metastases received the initial prescription dose of 35 Gy, and dose was then escalated to 40 Gy for 7 more patients with 7 liver metastases. An additional 19 postprotocol patients with 22 liver metastases were treated to 40 Gy in a single fraction. Patients were followed for toxicity and underwent serial imaging to assess local control.

RESULTS

Median imaging follow-up for the combined cohort (n = 33, 39 lesions) was 25.9 months; 38.9 months for protocol patients and 20.2 months for postprotocol patients. Median lesion size was 2.0 cm (range, 0.5-5.0 cm). There were no dose-limiting toxicities observed for protocol patients, and only 3 grade 2 toxicities were observed in the entire cohort, with no grade ≥3 toxicities attributable to treatment. Four-year actuarial local control of irradiated lesions in the entire cohort was 96.6%, 100% in the protocol group and 92.9% in the subsequent patients. Two-year overall survival for all treated patients was 82.0%.

CONCLUSIONS

For selected patients with liver metastases, single-fraction SABR at doses of 35 and 40 Gy was safe and well-tolerated, and shows excellent local control with long-term follow-up; results in subsequent patients treated with single-fraction SABR doses of 40 Gy confirmed our earlier results.

Modern therapeutic approaches for the treatment of malignant liver tumours

Malignant liver tumours include a wide range of primary and secondary tumours. Although surgery remains the mainstay of curative treatment, modern therapies integrate a variety of neoadjuvant and adjuvant strategies and have achieved dramatic improvements in survival. Extensive tumour loads, which have traditionally been considered unresectable, are now amenable to curative treatment through systemic conversion chemotherapies followed by a variety of interventions such as augmentation of the healthy liver through portal vein occlusion, staged surgeries or ablation modalities. Liver transplantation is established in selected patients with hepatocellular carcinoma but is now emerging as a promising option in many other types of tumour such as perihilar cholangiocarcinomas, neuroendocrine or colorectal liver metastases. In this Review, we summarize the available therapies for the treatment of malignant liver tumours, with an emphasis on surgical and ablative approaches and how they align with other therapies such as modern anticancer drugs or radiotherapy. In addition, we describe three complex case studies of patients with malignant liver tumours. Finally, we discuss the outlook for future treatment, including personalized approaches based on molecular tumour subtyping, response to targeted drugs, novel biomarkers and precision surgery adapted to the specific tumour.

Stereotactic Ablative Radiotherapy Fractionation for Hepatocellular Carcinoma in the United States

Introduction This study aims to analyze the patterns of care, including fractionation and utilization, of hypofractionated stereotactic ablative radiotherapy (SABR) in the treatment of hepatocellular carcinoma (HCC). Methods The National Cancer Database was queried for patients diagnosed with HCC from 2004 to 2014 and treated with SABR in three, four, or five fractions in 15-20Gy, 10-13Gy, or 6-12Gy per fraction, respectively. Patients with stage IV and Charlson-Deyo Comorbidity Index > 0 were excluded in order to avoid bias resulting from the selection of poorer prognosis patients. The patients were then stratified based on several characteristics including biologically equivalent doses (BEDs) of =/> 100 Gy and <100 Gy to determine whether there was an association with overall survival (OS) and a multivariable analysis (MVA) was performed to assess for potential confounding factors.  Results There were 462 patients identified in whom the most common SABR fractionation regimen was 10Gy x five fractions (25.3%), followed by 8Gy x five fractions (17.7%), and 15-16Gy x three fractions (26.4%). A total of 152 patients were treated to a BED < 100Gy, which was associated with a median OS of 20.8 months (95% CI 14.55-27.11). Three hundred and ten patients were treated to a BED =/> 100Gy, which was associated with a median OS of 30.8 months (95% CI 5.25-32.08). On MVA, BED =/> 100Gy was not significantly associated with improved OS (HR 0.85, 95% CI 0.64-1.14, p = 0.28). Factors that were associated with significantly worse survival were tumor size in the largest quartile (HR 2.197 CI 1.440-3.354, p < 0.0001) and T3a disease (HR 2.474 CI 1.472-4.158, p = 0.001 compared to T1).  Conclusion SABR fractionation schemes vary widely, but are most commonly 10Gy x five fractions followed by 8Gy x five fractions and 15Gy x three fractions. BED of at least 100Gy is not associated with improved OS. Further studies are needed to best identify the optimal SABR dose and fractionation.

Dosimetric assessment of patient-specific breath-hold reproducibility on liver motion for SBRT planning

PURPOSE

To investigate the impact of breath-hold reproducibility on liver motion using a respiratory motion management device.

METHODS

Forty-four patients with hepatic tumors, treated with SBRT with breath-hold, were randomly selected for this study. All patients underwent three consecutive computed tomography (CT) scans using active breath-hold coordinator (ABC) with three repeated single breath-hold during simulation. The three CT scans were labeled as ABC1-CT, ABC2-CT, and ABC3-CT. Displacements of centroids of the entire livers among the three ABC-CTs were measured as a surrogate for intrafractional motion. For each patient, two different treatment plans were prepared: (a) a clinical plan using a 5-mm expansion of an ITV that encompassed all three GTVs from each of the three ABC-CTs, and (b) a research plan using a 5-mm expansion of the GTV from only ABC1-CT to create PTV. The clinical plan acceptance criteria were that 95% of the PTV and 99% of the GTV received 100% of the prescription dose. Dosimetric endpoints were analyzed and compared for the two plans.

RESULTS

All shifts in the medial-lateral direction (range: -3.9 to 2.0 mm) were within 5 mm while 7% of shifts in the anterior-posterior direction (range: -10.5 to 16.7 mm) and 11% of shifts in the superior-inferior direction (range: -17.0 to 8.7 mm) exceeded 5 mm. Six patients (14%) had an intrafraction motion greater than 5 mm in any direction. For these six patients, if a plan was created based on a PTV from a single CT (ex. ABC1-CT), 5 of 12 GTVs captured from other ABC-CTs would fail to meet the clinical acceptance criteria due to poor breath-hold reproducibility.

CONCLUSIONS

Non-negligible intrafractional motion occurs in patients with poor breath-hold reproducibility. To identify this subgroup of patients, acquiring three CTs with active breath-hold during simulation is a feasible practical method.

Proton Beam Therapy in Liver Malignancies

PURPOSE OF REVIEW

Proton beam therapy (PBT) allows for improved sparing of surrounding normal tissues compared with X-ray-based radiation therapy. This is especially important in the setting of liver malignancies, where an increase in integral dose leads to a higher risk of radiation-induced liver disease (RILD) as well as close proximity to vital gastrointestinal (GI) organs.

RECENT FINDINGS

We have data from multiple centers demonstrating that PBT can safely deliver high, ablative doses of radiation therapy conferring excellent local control with good tolerance of treatment. PBT is an effective treatment with longstanding evidence of efficacy that is increasing in availability.

A retrospective cohort study of low-dose intensity-modulated radiotherapy for unresectable liver metastases

OBJECTIVE

To evaluate the efficacy and toxicity of intensity-modulated radiotherapy (IMRT) for the treatment of unresectable liver metastases.

METHODS

Twenty-five patients with unresectable liver metastases treated with IMRT were enrolled from January 2003 to September 2016. The median longest diameter of the lesions was 3.3 cm (range, 1.6-16.7 cm). The fraction dose ranged from 2 to 5.2 Gy, with a median total dose of 50 Gy (range, 30-60 Gy).

RESULTS

The median follow-up was 9.2 months (range, 2.1-48.8 months). The overall survival rates at 1 and 2 years were 46.4% and 27.4%, respectively. The 1-year local control rate was 69.8%. The 1-year progression-free survival rate was 26.3%. One patient had grade 4 liver dysfunction. One case of grade 4 leukopenia and one case of grade 3 leukopenia occurred, and one case of grade 3 leukopenia and thrombocytopenia was observed.

CONCLUSION

IMRT may be a promising and safe treatment for unresectable liver metastases and can be used as a treatment option.

Image quality evaluation of in-treatment four-dimensional cone-beam computed tomography in volumetric-modulated arc therapy for stereotactic body radiation therapy

In this study, the image quality of in-treatment four-dimensional cone-beam computed tomography (In-4D-CBCT) obtained with various prescription doses (PDs) were quantitatively evaluated in volumetric-modulated arc therapy (VMAT) for stereotactic body radiation therapy (SBRT) of the lungs and liver. To assess image quality, we used a dynamic thorax phantom and three-dimensional (3D) abdominal phantom; In-4D-CBCT images were acquired with various PDs (from 5 to 12 Gy). The In-4D-CBCT with various PDs were compared with the reference images (pre-4D-CBCT). The image quality was evaluated using the signal-to-noise ratio (SNR), the contrast-to-noise ratio (CNR), and the Dice similarity coefficient (DSC). The fiducial marker positions with various PDs were compared with those of the reference images. For the dynamic thorax phantom, the difference between pre- and In-4D-CBCT in terms of SNR and CNR decreased, as the PD increased from 6 to 12 Gy. The median DSC ranged from 0.7 to 0.74, and showed good similarity. For the 3D abdominal phantom, the difference between pre- and In-4D-CBCT in terms of SNR and CNR decreased as the PD increased from 5 to 6 Gy; conversely, it increased as the PD increased from 7 to 8 Gy. The fiducial marker positions were within 1.0 mm for all PDs. We concluded that the image quality of In-4D-CBCT degraded compared with the reference image; however, it was sufficiently accurate for assessing the intra-fractional tumor position in VMAT for SBRT of the lungs and liver both in terms of the target volume similarity and accuracy of the fiducial marker position.

Estimating intrafraction tumor motion during fiducial-based liver stereotactic radiotherapy via an iterative closest point (ICP) algorithm

BACKGROUND

Tumor motion may compromise the accuracy of liver stereotactic radiotherapy. In order to carry out a precise planning, estimating liver tumor motion during radiotherapy has received a lot of attention. Previous approach may have difficult to deal with image data corrupted by noise. The iterative closest point (ICP) algorithm is widely used for estimating the rigid registration of three-dimensional point sets when these data were dense or corrupted. In the light of this, our study estimated the three-dimensional (3D) rigid motion of liver tumors during stereotactic liver radiotherapy using reconstructed 3D coordinates of fiducials based on the ICP algorithm.

METHODS

Four hundred ninety-five pairs of orthogonal kilovoltage (KV) images from the CyberKnife stereo imaging system for 12 patients were used in this study. For each pair of images, the 3D coordinates of fiducial markers inside the liver were calculated via geometric derivations. The 3D coordinates were used to calculate the real-time translational and rotational motion of liver tumors around three axes via an ICP algorithm. The residual error was also investigated both with and without rotational correction.

RESULTS

The translational shifts of liver tumors in left-right (LR), anterior-posterior (AP),and superior-inferior (SI) directions were 2.92 ± 1.98 mm, 5.54 ± 3.12 mm, and 16.22 ± 5.86 mm, respectively; the rotational angles in left-right (LR), anterior-posterior (AP), and superior-inferior (SI) directions were 3.95° ± 3.08°, 4.93° ± 2.90°, and 4.09° ± 1.99°, respectively. Rotational correction decreased 3D fiducial displacement from 1.19 ± 0.35 mm to 0.65 ± 0.24 mm (P<0.001).

CONCLUSIONS

The maximum translational movement occurred in the SI direction. Rotational correction decreased fiducial displacements and increased tumor tracking accuracy.

[Liver stereotactic body radiotherapy: Clinical features and technical consequences, results. Which treatment machine in which situation?]

Liver stereotactic body radiotherapy is a developing technique for the treatment of primary tumours and metastases. Its implementation is complex because of the particularities of the treated organ and the comorbidities of the patients. However, this technique is a treatment opportunity for patients otherwise in therapeutic impasse. The scientific evidence of liver stereotactic body radiotherapy has been considered by the French health authority as insufficient for its widespread use outside specialized and experienced centers, despite a growing and important number of retrospective and prospective studies, but few comparative data. This article focuses on the specific features of stereotactic body radiotherapy for liver treatments and the results of published studies of liver stereotactic body radiotherapy performed with classic linear accelerators and dedicated radiosurgery units.

Clinical impact of removing respiratory motion during liver SABR

Background

Liver tumors are subject to motion with respiration, which is typically accounted for by increasing the target volume. The prescription dose is often reduced to keep the mean liver dose under a threshold level to limit the probability of radiation induced liver toxicity. A retrospective planning study was performed to determine the potential clinical gains of removal of respiratory motion from liver SABR treatment volumes, which may be achieved with gating or tumor tracking.

Methods

Twenty consecutive liver SABR patients were analysed. The treated PTV included the GTV in all phases of respiration (ITV) with a 5 mm margin. The goal prescription was 50Gy/5# (BED 100 Gy₁₀) but was reduced by 2.5 Gy increments to meet liver dose constraints. Elimination of motion was modelled by contouring the GTV in the expiration phase only, with a 5 mm PTV margin. All patients were replanned using the no-motion PTV and tumor dose was escalated to higher prescription levels where feasible given organ-at-risk constraints. For the cohort of patients with metastatic disease, BED gains were correlated to increases in tumour control probability (TCP). The effect of the gradient of the TCP curve on the magnitude of TCP increase was evaluated by repeating the study for an additional prescription structure, 54Gy/3# (BED 151 Gy₁₀).

Results

Correlation between PTV size and prescribed dose exists; PTVs encompassing < 10% of the liver could receive the highest prescription level. A monotonically increasing correlation (Spearman’s rho 0.771, p = 0.002) between the degree of PTV size reduction and motion vector magnitude was observed for GTV sizes <100cm³. For 11/13 patients initially planned to a decreased prescription, tumor dose escalation was possible (5.4Gy₁₀–21.4Gy₁₀ BED) using the no-motion PTV. Dose escalation in excess of 20 Gy₁₀ increased the associated TCP by 5% or more. A comparison of TCP gains between the two fractionation schedules showed that, for the same patient geometry, the absolute increase in BED was the overarching factor rather than the gradient of the TCP curve.

Conclusions

In liver SABR treatments unable to be prescribed optimal dose due to exceeding mean liver thresholds, eliminating respiratory motion allowed dose escalation in the majority of patients studied and substantially increased TCP.

Buforin IIb induced cell cycle arrest in liver cancer

The inhibitory effect of buforin IIb on different types of cancer, although not liver cancer, has been demonstrated previously. The aim of the present study was to investigate the effects of buforin IIb on the progression of liver cancer. The human liver cancer cell line HepG2 was treated with purified buforin IIb and the cell activity was determined by MTT, colony formation and transwell assays. The protein expression levels of cyclin-dependent kinases (CDKs) and cyclins were analyzed by western blotting and immunofluorescent cell staining. A tumor growth model was constructed using nude mice, and buforin IIb treatment was administered. The levels of CDK2 and cyclin A in the tumor tissues were detected by western blotting. Buforin IIb treatment depressed cell viability and colony formation and induced apoptosis significantly, and 1.0 µM concentration of buforin IIb was found to be the optimal dosage. The cell cycle was arrested at the G2/M phase following buforin IIb treatment. CDK2 and cyclin A were downregulated by treatment of the cells with 1.0 µM buforin IIb for 24 h. Treatment with buforin IIb also inhibited the migration of liver cancer cells in vitro. Furthermore, 50 nmol buforin IIb injection suppressed HepG2 cell subcutaneous tumor growth in the nude mouse model. Similar to the in vitro results, buforin IIb injection reduced the expression of CDK2 and cyclin A in the tumor tissue. these results demonstrate that buforin IIb inhibited liver cancer cell growth via the regulation of CDK2 and cyclin A expression.

The impact of local control on overall survival after stereotactic body radiotherapy for liver and lung metastases from colorectal cancer: a combined analysis of 388 patients with 500 metastases

BACKGROUND

The aim of this analysis was to model the effect of local control (LC) on overall survival (OS) in patients treated with stereotactic body radiotherapy (SBRT) for liver or lung metastases from colorectal cancer.

METHODS

The analysis is based on pooled data from two retrospective SBRT databases for pulmonary and hepatic metastases from 27 centers from Germany and Switzerland. Only patients with metastases from colorectal cancer were considered to avoid histology as a confounding factor. An illness-death model was employed to model the relationship between LC and OS.

RESULTS

Three hundred eighty-eight patients with 500 metastatic lesions (lung n = 209, liver n = 291) were included and analyzed. Median follow-up time for local recurrence assessment was 12.1 months. Ninety-nine patients with 112 lesions experienced local failure. Seventy-one of these patients died after local failure. Median survival time was 27.9 months in all patients and 25.4 months versus 30.6 months in patients with and without local failure after SBRT. The baseline risk of death after local failure exceeds the baseline risk of death without local failure at 10 months indicating better survival with LC.

CONCLUSION

In CRC patients with lung or liver metastases, our findings suggest improved long-term OS by achieving metastatic disease control using SBRT in patients with a projected OS estimate of > 12 months.

Outcomes after hypofractionated stereotactic radiotherapy for colorectal cancer oligometastases

BACKGROUND AND OBJECTIVES

To assess the efficacy and the effect of biologic effective dose (BED) on outcomes treated by hypofractionated stereotactic radiotherapy for colorectal cancer (CRC) oligometastases.

METHODS

Patients with CRC oligometastases treated at our hospital between 2009 and 2016 were included. The relationship between BED and risk of local recurrence was assessed. Recursive partitioning analysis (RPA) was used to evaluate the effect of BED on outcomes.

RESULTS

A total of 48 patients were included in this study. Median follow-up time of surviving patient was 15 months (range, 3-82 months). The 1-year local control rate was 85%. The risk of local recurrence decreased sharply when BED was >90 Gy₁₀ . RPA showed BED of 100 Gy ₁₀ was the appropriate dose for recurrence risk stratification. BED ≥ 100 Gy ₁₀ was significantly better than BED < 100 Gy ₁₀ for achieving 1-year local control (94.4% vs 63.2%; P = 0.022) and 1-year OS (100% vs 73.4%; P = 0.028). One patient who received long-term antiangiogenic treatment died of massive intestinal hemorrhage; no other grade 3 or above early or late events were observed.

CONCLUSIONS

Hypofractionated stereotactic radiotherapy provides favorable outcomes with acceptable toxicities in CRC oligometastases. BED ≥ 100 Gy is associated with better outcomes.

Single fraction carbon ion radiotherapy for colorectal cancer liver metastasis: A dose escalation study

Prognosis is usually grim for those with liver metastasis from colorectal cancer (CRC) who cannot receive resection. Radiation therapy can be an option for those unsuitable for resection, with carbon ion radiotherapy (CIRT) being more effective and less toxic than X-ray due to its physio-biological characteristics. The objective of this study is to identify the optimal dose of single fraction CIRT for colorectal cancer liver metastasis. Thirty-one patients with liver metastasis from CRC were enrolled in the present study. Twenty-nine patients received a single-fraction CIRT, escalating the dose from 36 Gy (RBE) in 5% to 10% increments until unacceptable incidence of dose-limiting toxicity was observed. Dose-limiting toxicity was defined as grade ≥3 acute toxicity attributed to radiotherapy. The prescribed doses were as follows: 36 Gy (RBE) (3 cases), 40 Gy (2 cases), 44 Gy (4 cases), 46 Gy (6 cases), 48 Gy (3 cases), 53 Gy (8 cases) and 58 Gy (3 cases). Dose-limiting toxicity was not observed, but late grade 3 liver toxicity due to biliary obstruction was observed in 2 patients at 53 Gy (RBE). Both cases had lesions close to the hepatic portal region, and, therefore, the dose was escalated to 58 Gy (RBE), limited to peripheral lesions. The 3-year actuarial overall survival rate of all 29 patients was 78%, and the median survival time was 65 months. Local control improved significantly at ≥53 Gy (RBE), with a 3-year actuarial local control rate of 82%, compared to 28% in lower doses. Treatment for CRC liver metastasis with single-fraction CIRT appeared to be safe up to 58 Gy (RBE) as long as the central hepatic portal region was avoided.

Dose escalation in extracranial stereotactic ablative radiotherapy (DESTROY-1): A multiarm Phase I trial

OBJECTIVE:

A multiarm Phase I clinical trial was performed to define the maximum tolerated dose (MTD) of stereotactic body radiotherapy (SBRT) delivered by non-coplanar conformal beams or volumetric modulated arc therapy technique in seven predefined clinical settings.

METHODS:

The (a) and (b) arms investigated primary and metastatic lung cancer differentiated by site of onset, arm (c) included primary or metastatic lesions outside the thorax, the (d) and (e) arms were for in-field reirradiation of recurrence, and finally, the (f) and (g) arms were for boost irradiation to the lesions after an adjuvant RT prescribed dose. A 4 months cut-off after previous irradiation course was fixed to distinguish the boost from the retreatment (<4 vs >4 months, respectively). Patients were prospectively enrolled in study arms according to tumor site, clinical stage and previous treatment. The total dose prescribed to the isocenter, ranged from 20 to 50 Gy according to the protocol design and the doses per fraction ranged from 4 to 10 Gy in 5 days.

RESULTS:

A total of 281 patients (M/F: 167/114; median age: 69 years) with 376 lesions underwent SBRT. No acute toxicity was reported in 175 patients (62.3%) while 106 (37.7%) experienced only low-grade (G < 2) acute toxicity. Four patients (all previously irradiated in the same site) showed >Grade 2 toxicity within 6 months from SBRT. With a median follow-up of 19 months, 204 patients (72.6%) did not experience late toxicity, and 77 (27.4%) experienced low grade late toxicity. On per-lesion basis, the 12-and 24 months actuarial local control inside the SBRT field were 84.3 and 73.7 %, respectively.

CONCLUSIONS:

SBRT delivered in five consecutive fractions up to the doses evaluated is well tolerated. The MTD was reached in four (a, b, c and f) of the seven study arms. Recruitment for (d), (e) and (g) arms is still ongoing.

ADVANCES IN KNOWLEDGE:

In a prospective dose-escalation trial, the MTD of 50 Gy/10 Gy fraction and 35 Gy/7 Gy fraction were defined for primary and metastatic lesions and as boost after prior RT dose ≤50 Gy, respectively.

Oligometastatic breast cancer

Metastatic breast cancer (MBC) is considered as incurable. The group of patients with oligometastatic disease (a few metastatic lesions and organs involved) apparently have better prognosis. It is claimed that, these patients could be treated with curative intent, and multidisciplinary aggressive approach should be considered. Despite the lack of strong data it is increasingly accepted in clinical practice. Currently, the appropriate candidate would be young woman with good performance status, low tumour burden with long disease-free interval. Because for them with already favorable nature of their disease, aggressive treatment has greater chances to improve survivals. Local ablative treatment (radiotherapy/surgery) has a crucial role in this setting. Available mainly from retrospective in nature long-term results are encouraging but need confirmation in prospective randomized studies. In this review, I discuss the definition of oligometastatic disease, its nature, currently available data and ongoing prospective randomized trials dedicated to oligometastatic breast cancer patients.

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.

Hypofractionated stereotactic radiotherapy for oligometastatic patients: developing of a response predictive model

OBJECTIVES

Treatment of oligometastatic patients is a current challenge in radiation oncology. Aim of this study is to define a dose-response relationship for hypofractionated radiotherapy of oligometastases.

METHODS

Retrospective analysis of metastases treated by hypofractionated stereotactic radiotherapy was performed. Delivered dose was calculated both as biological effective dose (BED₁₀), and as ratio between BED₁₀ and the logarithm of metastasis volume (BED₁₀ logVolume Ratio, BVR). Two dose-response models were defined by logistic regression. The fitted outcome was the Metastases Complete Response (MCR). Performances of the models were assessed by area under the receiver operating curve (AUC) and by bootstrap calibration of original data. BED₁₀ and BVR impact on survival outcomes has been evaluated.

RESULTS

Fifty-three patients with 79 metastases were analyzed. AUC and calibration of BVR-based logistic model showed better accuracy in predicting MCR with respect to BED₁₀-based model. No significant difference between the two ROCs was observed (De Long test p value > 0.05), but significant discordance in calibration resulted in the BED₁₀ model (p value < 0.05 in Hosmer-Lemeshow Goodness of fit test). BVR returned also better results in multivariate analyses for survival outcomes.

CONCLUSIONS

The ratio between BED₁₀ and the logarithm of metastasis volume (BVR), as a corrective factor for fitting the probability of metastases response to stereotactic radiotherapy, could be a tool for evaluating and prescribing treatments for oligometastatic disease. BVR can be useful for producing more reliable survival statistics too.

A Multi-Institutional Experience of MR-Guided Liver Stereotactic Body Radiation Therapy

Purpose

Daily magnetic resonance (MR)–guided radiation has the potential to improve stereotactic body radiation therapy (SBRT) for tumors of the liver. Magnetic resonance imaging (MRI) introduces unique variables that are untested clinically: electron return effect, MRI geometric distortion, MRI to radiation therapy isocenter uncertainty, multileaf collimator position error, and uncertainties with voxel size and tracking. All could lead to increased toxicity and/or local recurrences with SBRT. In this multi-institutional study, we hypothesized that direct visualization provided by MR guidance could allow the use of small treatment volumes to spare normal tissues while maintaining clinical outcomes despite the aforementioned uncertainties in MR-guided treatment.

Methods and materials

Patients with primary liver tumors or metastatic lesions treated with MR-guided liver SBRT were reviewed at 3 institutions. Toxicity was assessed using National Cancer Institute Common Terminology Criteria for Adverse Events Version 4. Freedom from local progression (FFLP) and overall survival were analyzed with the Kaplan-Meier method and χ² test.

Results

The study population consisted of 26 patients: 6 hepatocellular carcinomas, 2 cholangiocarcinomas, and 18 metastatic liver lesions (44% colorectal metastasis). The median follow-up was 21.2 months. The median dose delivered was 50 Gy at 10 Gy/fraction. No grade 4 or greater gastrointestinal toxicities were observed after treatment. The 1-year and 2-year overall survival in this cohort is 69% and 60%, respectively. At the median follow-up, FFLP for this cohort was 80.4%. FFLP for patients with hepatocellular carcinomas, colorectal metastasis, and all other lesions were 100%, 75%, and 83%, respectively.

Conclusions

This study describes the first clinical outcomes of MR-guided liver SBRT. Treatment was well tolerated by patients with excellent local control. This study lays the foundation for future dose escalation and adaptive treatment for liver-based primary malignancies and/or metastatic disease.

Beyond the Knife: The Evolving Nonsurgical Management of Oligometastatic Colorectal Cancer

In patients with liver-limited oligometastatic disease, the goal of treatment can be curative intent. Historically, this was accomplished in patients presenting with upfront resectable disease. The availability of increasingly efficacious chemotherapy and biologic combinations with encouraging response rates led to the potential to convert unresectable disease to resectability. Beyond the backbone of surgery, we now have a portfolio of locoregional strategies to consider.From an interventional radiology perspective, the use of portal vein embolization can facilitate hypertrophy of the liver in anticipation of resection, thus converting unresectable disease to one amenable to a surgical approach with curative intent. Technological advances in liver-directed ablative therapies have afforded the possibility of eliminate radiographically evident disease with the hope for long-term disease control. Advanced radiotherapy techniques are further increasing the therapeutic options for patients with metastatic colorectal cancer. Improvements in external-beam radiotherapy over the past 2 decades include image-guided radiotherapy, intensity-modulated radiotherapy, stereotactic body radiotherapy, and proton-beam therapy. Finally, selective internal radiation therapy (SIRT) with microspheres labeled with the β-emitter ⁹⁰Y enable targeted delivery of radiation to hepatic tumors. A coordinated multidisciplinary approach is required to integrate these nonsurgical adjuncts in an evidence-based manner to optimize outcomes for patients with potentially resectable metastatic disease. In this article, we summarize recent developments in systemic therapy, radiotherapy, and interventional liver-directed therapies that have changed the treatment landscape for patients with oligometastatic colorectal cancer.

The SBRT database initiative of the German Society for Radiation Oncology (DEGRO): patterns of care and outcome analysis of stereotactic body radiotherapy (SBRT) for liver oligometastases in 474 patients with 623 metastases

BACKGROUND

The intent of this pooled analysis as part of the German society for radiation oncology (DEGRO) stereotactic body radiotherapy (SBRT) initiative was to analyze the patterns of care of SBRT for liver oligometastases and to derive factors influencing treated metastases control and overall survival in a large patient cohort.

METHODS

From 17 German and Swiss centers, data on all patients treated for liver oligometastases with SBRT since its introduction in 1997 has been collected and entered into a centralized database. In addition to patient and tumor characteristics, data on immobilization, image guidance and motion management as well as dose prescription and fractionation has been gathered. Besides dose response and survival statistics, time trends of the aforementioned variables have been investigated.

RESULTS

In total, 474 patients with 623 liver oligometastases (median 1 lesion/patient; range 1–4) have been collected from 1997 until 2015. Predominant histologies were colorectal cancer (n = 213 pts.; 300 lesions) and breast cancer (n = 57; 81 lesions). All centers employed an SBRT specific setup. Initially, stereotactic coordinates and CT simulation were used for treatment set-up (55%), but eventually were replaced by CBCT guidance (28%) or more recently robotic tracking (17%). High variance in fraction (fx) number (median 1 fx; range 1–13) and dose per fraction (median: 18.5 Gy; range 3–37.5 Gy) was observed, although median BED remained consistently high after an initial learning curve. Median follow-up time was 15 months; median overall survival after SBRT was 24 months. One- and 2-year treated metastases control rate of treated lesions was 77% and 64%; if maximum isocenter biological equivalent dose (BED) was greater than 150 Gy EQD2Gy, it increased to 83% and 70%, respectively. Besides radiation dose colorectal and breast histology and motion management methods were associated with improved treated metastases control.

CONCLUSION

After an initial learning curve with regards to total cumulative doses, consistently high biologically effective doses have been employed translating into high local tumor control at 1 and 2 years. The true impact of histology and motion management method on treated metastases control deserve deeper analysis. Overall survival is mainly influenced by histology and metastatic tumor burden.

Strategies for prediction and mitigation of radiation-induced liver toxicity

Although well described in the 1960s, liver toxicity secondary to radiation therapy, commonly known as radiation-induced liver disease (RILD), remains a major challenge. RILD encompasses two distinct clinical entities, a 'classic' form, composed of anicteric hepatomegaly, ascites and elevated alkaline phosphatase; and a 'non-classic' form, with liver transaminases elevated to more than five times the reference value, or worsening of liver metabolic function represented as an increase of 2 or more points in the Child-Pugh score classification. The risk of occurrence of RILD has historically limited the applicability of radiation for the treatment of liver malignancies. With the development of 3D conformal radiation therapy, which allowed for partial organ irradiation based on computed tomography treatment planning, there has been a resurgence of interest in the use of liver irradiation. Since then, a large body of evidence regarding the liver tolerance to conventionally fractionated radiation has been produced, but severe liver toxicities has continued to be reported. More recently, improvements in diagnostic imaging, radiation treatment planning technology and delivery systems have prompted the development of stereotactic body radiotherapy (SBRT), by which high doses of radiation can be delivered with high target accuracy and a steep dose gradient at the tumor - normal tissue interface, offering an opportunity of decreasing toxicity rates while improving tumor control. Here, we present an overview of the role SBRT has played in the management of liver tumors, addressing the challenges and opportunities to reduce the incidence of RILD, such as adaptive approaches and machine-learning-based predictive models.

Strategic application of radiotherapy for hepatocellular carcinoma

With increasing clinical use, radiotherapy (RT) has been considered reliable and effective method for hepatocellular carcinoma (HCC) treatment, depending on extent of disease and patient characteristics. RT for HCC can improve therapeutic outcomes through excellent local control, downstaging, conversion from unresectable to resectable status, and treatments of unresectable HCCs with vessel invasion or multiple intrahepatic metastases. In addition, further development of modern RT technologies, including image-guided radiotherapy (IGRT), intensity-modulated radiotherapy (IMRT), and stereotactic body radiotherapy, has expanded the indication of RT. An essential feature of IGRT is that it allows image guidance therapy through in-room images obtained during radiation delivery. Compared with 3D-conformal RT, distinctions of IMRT are inverse treatment planning process and use of a large number of treatment fields or subfields, which provide high precision and exquisitely conformal dose distribution. These modern RT techniques allow more precise treatment by reducing inter- and intra-fractional errors resulting from daily changes and irradiated dose at surrounding normal tissues. More recently, particle therapy has been actively investigated to improve effectiveness of RT. This review discusses modern RT strategies for HCC, as well as optimal selection of RT in multimodal approach for HCC.

Impact of audiovisual biofeedback on interfraction respiratory motion reproducibility in liver cancer stereotactic body radiotherapy

INTRODUCTION

Irregular breathing motion exacerbates uncertainties throughout a course of radiation therapy. Breathing guidance has demonstrated to improve breathing motion consistency. This was the first clinical implementation of audiovisual biofeedback (AVB) breathing guidance over a course of liver stereotactic body radiotherapy (SBRT) investigating interfraction reproducibility.

METHODS

Five liver cancer patients underwent a screening procedure prior to CT sim during which patients underwent breathing conditions (i) AVB, or (ii) free breathing (FB). Whichever breathing condition was more regular was utilised for the patient's subsequent course of SBRT. Respiratory motion was obtained from the Varian respiratory position monitoring (RPM) system (Varian Medical Systems). Breathing motion reproducibility was assessed by the variance of displacement across 10 phase-based respiratory bins over each patient's course of SBRT.

RESULTS

The screening procedure yielded the decision to utilise AVB for three patients and FB for two patients. Over the course of SBRT, AVB significantly improved the relative interfraction motion by 32%, from 22% displacement difference for FB patients to 15% difference for AVB patients. Further to this, AVB facilitated sub-millimetre interfraction reproducibility for two AVB patients.

CONCLUSION

There was significantly less interfraction motion with AVB than FB. These findings demonstrate that AVB is potentially a valuable tool in ensuring reproducible interfraction motion.

Local Control After Stereotactic Body Radiation Therapy for Liver Tumors

PURPOSE

To quantitatively evaluate published experiences with hepatic stereotactic body radiation therapy (SBRT), to determine local control rates after treatment of primary and metastatic liver tumors and to examine whether outcomes are affected by SBRT dosing regimen.

METHODS AND MATERIALS

We identified published articles that reported local control rates after SBRT for primary or metastatic liver tumors. Biologically effective doses (BEDs) were calculated for each dosing regimen using the linear-quadratic equation. We excluded series in which a wide range of BEDs was used. Individual lesion data for local control were extracted from actuarial survival curves, and data were aggregated to form a single dataset. Actuarial local control curves were generated using the Kaplan-Meier method after grouping lesions by disease type and BED (<100 Gy₁₀ vs >100 Gy₁₀). Comparisons were made using log-rank testing.

RESULTS

Thirteen articles met all inclusion criteria and formed the dataset for this analysis. The 1-, 2-, and 3-year actuarial local control rates after SBRT for primary liver tumors (n = 431) were 93%, 89%, and 86%, respectively. Lower 1- (90%), 2- (79%), and 3-year (76%) actuarial local control rates were observed for liver metastases (n = 290, log-rank P = .011). Among patients treated with SBRT for primary liver tumors, there was no evidence that local control is influenced by BED within the range of schedules used. For liver metastases, on the other hand, outcomes were significantly better for lesions treated with BEDs exceeding 100 Gy₁₀ (3-year local control 93%) than for those treated with BEDs of ≤100 Gy₁₀ (3-year local control 65%, P < .001).

CONCLUSIONS

Stereotactic body radiation therapy for primary liver tumors provides high rates of durable local control, with no clear evidence for a dose-response relationship among commonly utilized schedules. Excellent local control rates are also seen after SBRT for liver metastases when BEDs of >100 Gy₁₀ are utilized.

UK Consensus on Normal Tissue Dose Constraints for Stereotactic Radiotherapy

Six UK studies investigating stereotactic ablative radiotherapy (SABR) are currently open. Many of these involve the treatment of oligometastatic disease at different locations in the body. Members of all the trial management groups collaborated to generate a consensus document on appropriate organ at risk dose constraints. Values from existing but older reviews were updated using data from current studies. It is hoped that this unified approach will facilitate standardised implementation of SABR across the UK and will allow meaningful toxicity comparisons between SABR studies and internationally.

Image quality of four-dimensional cone-beam computed tomography obtained at various gantry rotation speeds for liver stereotactic body radiation therapy with fiducial markers

In this study, qualities of 4D cone-beam CT (CBCT) images obtained using various gantry rotation speeds (GRSs) for liver stereotactic body radiation therapy (SBRT) with fiducial markers were quantitatively evaluated. Abdominal phantom containing a fiducial marker was moved along a sinusoidal waveform, and 4D-CBCT images were acquired with GRSs of 50-200° min^-1. We obtained the 4D-CBCT projection data from six patients who underwent liver SBRT and generated 4D-CBCT images at GRSs of 67-200° min^-1, by varying the number of projection data points. The image quality was evaluated based on the signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and structural similarity index (SSIM). The fiducial marker positions with different GRSs were compared with the setup values and a reference position in the phantom and clinical studies, respectively. The root mean square errors (RMSEs) were calculated relative to the reference positions. In the phantom study, the mean SNR, CNR, and SSIM decreased from 37.6 to 10.1, from 39.8 to 10.1, and from 0.9 to 0.7, respectively, as the GRS increased from 50 to 200° min^-1. The fiducial marker positions were within 2.0 mm at all GRSs. Similarly, in the clinical study, the mean SNR, CNR, and SSIM decreased from 50.4 to 13.7, from 24.2 to 6.0, and from 0.92 to 0.73, respectively. The mean RMSEs were 2.0, 2.1, and 3.6 mm for the GRSs of 67, 100, and 200° min^-1, respectively. We conclude that GRSs of 67 and 85° min^-1 yield images of acceptable quality for 4D-CBCT in liver SBRT with fiducial markers.

Impact of tumor size on outcome after stereotactic body radiation therapy for inoperable hepatocellular carcinoma

Stereotactic body radiation therapy (SBRT) for inoperable hepatocellular carcinoma (HCC) offers excellent local control rates. This study retrospectively analyzed the influence of different tumor size on treatment outcomes after SBRT.Between December 2008 and February 2014, 141 HCC patients were treated with Cyberknife SBRT. Patients were divided into 3 groups namely small tumors (≤4 cm), intermediate-sized (>4-<10 cm), and large (≥10 cm) tumors. Treatment outcomes, prognoses, and safety at each tumor size were compared and analyzed.A total of 52 patients with small tumors, 55 with intermediate tumors, and 34 patients with large tumors were retrospectively analyzed with a median follow-up of 16 months. Objective responses were achieved at 96.15%, 90.90%, and 76.47% for small, intermediate, and large tumors, respectively (P ≤ .0001) and the 3-year local control rates were 97.85%, 71.99%, and 82.14%, respectively (P = .0035). The 3-year overall survival rates were 50.26%, 45.29%, and 33.38% for small, intermediate, and large tumors, respectively (P = .3757). No significant differences were found in overall-survival, intra-hepatic recurrence free survival, disease-progression free survival, or distant metastasis-free survival.SBRT offers the best effective local control rate and response rate for small HCCs. However, tumor size did not significantly affect the overall survival rate, intra-hepatic recurrence free rate, or disease-progression free rate.

Analysis of the factors affecting the safety of robotic stereotactic body radiation therapy for hepatocellular carcinoma patients

Objective

The objective of this study was to investigate the safety of robotic stereotactic body radiation therapy (SBRT) for hepatocellular carcinoma (HCC) patients and its related factors.

Methods

A total of 74 HCC patients with Child-Turcotte-Pugh (CTP) Class A were included in a multi-institutional, single-arm Phase II trial (NCT 02363218) between February 2013 and August 2016. All patients received SBRT treatment at a dose of 45 Gy/3f. The liver function was compared before and after SBRT treatment by the analysis of adverse hepatic reactions and changes in CTP classification.

Results

After SBRT treatment, eight patients presented with decreases in CTP classification and 13 patients presented with ≥ grade 2 hepatic adverse reactions. For patients presenting with ≥ grade 2 hepatic adverse reactions, the total liver volume of ≤1,162 mL and a normal liver volume (total liver volume - gross tumor volume [GTV]) of ≤1,148 mL were found to be independent risk factors and statistically significant (P<0.05).

Conclusion

The total liver volume and normal liver volume are associated with the occurrence of ≥ grade 2 hepatic adverse reactions after SBRT treatment on HCC patients. Therefore, if the fractionated scheme of 45 Gy/3f is applied in SBRT for HCC patients, a total liver volume >1,162 mL and a normal liver volume >1,148 mL should be ensured to improve therapeutic safety.

[Local ablative radiotherapy of oligometastatic colorectal cancer]

BACKGROUND

Colorectal cancer (CRC) often presents as oligometastatic disease. Currently available intensive systemic treatment regimens, including combination chemotherapy and molecular targeted agents, result in tumor response and transient to long-term disease control in a high percentage of patients, thus raising the question of further management. Secondary resection and ablation, e.g. by surgery or radiofrequency may contribute to long-term survival and even be curative or at least allow a relevant chemotherapy-free interval. These approaches are often limited by the anatomical site, invasiveness and morbidity of the respective procedure. With stereotactic body radiotherapy (SBRT) metastases can be treated with very high efficiency in only a few sessions and achieving long-term control.

OBJECTIVES

Identification of clinical studies investigating the use of SBRT for treatment of oligometastases in CRC patients. Control rates in liver and lung metastases and survival after SBRT. Toxicity and side effects of the treatment.

MATERIAL AND METHODS

A literature search was carried out for prospective and retrospective studies on local SBRT.

RESULTS AND CONCLUSION

The SBRT procedure has become a valid treatment option for patients with oligometastatic CRC and should also be considered in clinical practice as an alternative to surgical treatment of metastases or other local ablative techniques.

[Stereotactic body radiotherapy for liver tumors: State of the art]

Thanks to the improvement in radiotherapy physics, biology, computing and imaging, patients presenting with liver tumors can be efficiently treated by radiation. Radiotherapy has been included in liver tumors treatment guidelines at all disease stages. Liver stereotactic radiotherapy has to be preferred to standard fractionated radiotherapy whenever possible, as potentially more efficient because of higher biological equivalent dose. Liver stereotactic radiotherapy planning and delivery require extensive experience and optimal treatment quality at every step, thus limiting its availability to specialized centres. Multicentre studies are difficult to develop due to a large technical heterogeneity. Respiratory management, image guidance and immobilization are considerations as important as machine type. The use of multimodal planning imaging is compulsory to achieve expected contouring quality. Treatment efficacy is difficult to assess following liver stereotactic radiotherapy, but local control is high and toxicity unusual. As a consequence, liver stereotactic radiotherapy is part of multimodal and multidisciplinary management of liver tumors.

Endoluminal and Interstitial Brachytherapy for the Treatment of Gastrointestinal Malignancies: a Systematic Review

Radiation therapy is an integral component in the multimodality management of many gastrointestinal (GI) cancers at all stages of clinical presentation. With recent advances in technology and radiation delivery, external beam radiation therapy (EBRT) can be delivered with reduced toxicity. However, despite these advances, EBRT doses are still limited by the presence of radiosensitive serial structures near clinical targets in the GI tract. Relative to EBRT techniques, brachytherapy techniques have a lower integral dose and more rapid fall-off, allowing for high-dose delivery with little normal tissue exposure. Given the unique characteristics of brachytherapy, it is an attractive strategy to treat GI malignancies. This review addresses the application of both high-dose rate brachytherapy (HDRBT) and low-dose rate brachytherapy (LDRBT) to multiple GI malignancies for both definitive and palliative management.