Protons versus Photons for Unresectable Hepatocellular Carcinoma: Liver Decompensation and Overall Survival

Proton Beam Therapy for Intrahepatic Cholangiocarcinoma: A Multicenter Prospective Registry Study in Japan

Introduction

Intrahepatic cholangiocarcinoma (ICC) can be treated with chemotherapy in unresectable cases, but outcomes are poor. Proton beam therapy (PBT) may provide an alternative treatment and has good dose concentration that may improve local control.

Methods

Fifty-nine patients who received initial PBT for ICC from May 2016 to June 2018 at nine centers were included in the study. The treatment protocol was based on the policy of the Japanese Society for Radiation Oncology. Forty patients received 72.6-76 Gy (RBE) in 20-22 fr, 13 received 74.0-76.0 Gy (RBE) in 37-38 fr, and 6 received 60-70.2 Gy (RBE) in 20-30 fr. Overall survival (OS) and progression-free survival (PFS) were estimated by Kaplan-Meier analysis.

Results

The 59 patients (35 men, 24 women; median age: 71 years; range: 41-91 years) had PS of 0 (n = 47), 1 (n = 10), and 2 (n = 2). Nine patients had hepatitis and all 59 cases were considered inoperable. The Child-Pugh class was A (n = 46), B (n = 7), and unknown (n = 6); the median maximum tumor diameter was 5.0 cm (range 2.0-15.2 cm); and the clinical stage was I (n = 12), II (n = 19), III (n = 10), and IV (n = 18). At the last follow-up, 17 patients were alive (median follow-up: 36.7 months; range: 24.1-49.9 months) and 42 had died. The median OS was 21.7 months (95% CI: 14.8-34.4 months). At the last follow-up, 37 cases had recurrence, including 10 with local recurrence. The median PFS was 7.5 months (95% CI: 6.1-11.3 months). In multivariable analyses, Child-Pugh class was significantly associated with OS and PFS, and Child-Pugh class and hepatitis were significantly associated with local recurrence. Four patients (6.8%) had late adverse events of grade 3 or higher.

Conclusion

PBT gives favorable treatment outcomes for unresectable ICC without distant metastasis and may be particularly effective in cases with large tumors.

Clinical and Dosimetric Results of Proton or Photon Radiation Therapy for Large (>5 cm) Hepatocellular Carcinoma: A Retrospective Analysis

PURPOSE

Our purpose was to report the clinical and dosimetric attributes of patients with large unresectable hepatocellular carcinoma (HCC) undergoing proton or photon radiation therapy.

METHODS AND MATERIALS

We retrospectively analyzed the outcomes and dosimetric indices of 159 patients with >5 cm nonmetastatic HCC who underwent definitive radiation therapy using either protons (N = 105) or photons (N = 54) between 2014 and 2018. Additional photon plans were performed in the 105 proton-treated patients using the same dose prescription criteria for intragroup dosimetric comparison.

RESULTS

After a median follow-up of 47 months, patients with biologically effective dose (BED10) ≥ 75 Gy exhibited significantly better local control (LC; 2-year: 85.6% vs 20.5%; P < .001), progression-free survival (PFS; median, 7.4 vs 3.2 months; P < .001), and overall survival (OS; median, 18.1 vs 7.3 months; P < .001) compared with those with BED10 < 75 Gy. Notably, proton-treated patients had a significantly higher BED10 (96 vs 67 Gy; P < .001) and improved LC (2-year: 88.5% vs 33.8%; P < .001), PFS (median, 7.4 vs 3.3 months; P = .001), and OS (median, 18.9 vs 8.3 months; P < .001) than those undergoing photon radiation therapy. Furthermore, patients treated with protons had significantly lower V1 of the liver (P < .001), mean upper gastrointestinal tract dose (P < .001), and mean splenic dose (P < .001), with significantly decreased incidences of radiation-induced liver disease (P = .007), grade ≥3 upper gastrointestinal bleeding (P = .001), and grade ≥3 lymphopenia (P = .003). On multivariate analysis, proton radiation therapy consistently correlated with superior LC (P < .001), PFS (P < .001), and OS (P < .001). In intragroup dosimetric comparison, photon plans demonstrated significantly higher mean liver dose (P < .001) compared with actually delivered proton treatments, and 72 (69%) of them had mean liver dose exceeding 28 Gy, which necessitated target dose de-escalation.

CONCLUSIONS

In the context of large HCC radiation therapy, a higher target BED10 was associated with improved outcomes. Notably, proton therapy has demonstrated the capability to deliver ablative doses while also being accompanied by fewer instances of severe toxicity.

Proton Beam Therapy for Hepatocellular Carcinoma: Multicenter Prospective Registry Study in Japan

PURPOSE

A prospective multicenter registry study was started May 2016 in Japan to evaluate the efficacy and safety of proton beam therapy (PBT) for hepatocellular carcinoma (HCC).

METHODS AND MATERIALS

Patients who received PBT for HCC from May 2016 to June 2018 were registered in the database of the Particle Beam Therapy Committee and Subcommittee of the Japanese Society for Radiation Oncology. Overall survival (OS), progression-free survival (PFS), and local recurrence were evaluated.

RESULTS

Of the 755 registered patients, 576 with initial PBT and no duplicate cancer were evaluated. At final follow-up, 322 patients were alive and 254 had died. The median follow-up period for survivors was 39 months (0-58 months). The median OS time of the 576 patients was 48.8 months (95% CI, 42.0-55.6 months) and the 1-, 2-, 3-, and 4-year OS rates were 83.8% (95% CI, 80.5%-86.6%), 68.5% (64.5%-72.2%), 58.2% (53.9%-62.2%), and 50.1% (44.9%-55.0%), respectively. Recurrence was observed in 332 patients, including local recurrence in 45 patients. The median PFS time was 14.7 months (95% CI, 12.4-17.0 months) and the 1-, 2-, 3-, and 4-year PFS rates were 55.2% (95% CI, 51.0%-59.2%), 37.5% (33.5%-41.5%), 30.2% (26.3%-34.2%), and 22.8% (18.5%-27.4%), respectively. The 1-, 2-, 3-, and 4-year OS rates were significantly higher for tumor size <5 versus 5 to 10 cm (P < .001) and <5 versus ≥10 cm (P < .001); Child-Pugh score A/B versus C (P < .001); and distance of the tumor from the gastrointestinal tract <1 versus 1 to 2 cm (P < .008) and <1 versus >2 cm (P < .001). At final follow-up, 27 patients (4.7%) had late adverse events of grade 3 or higher, with liver failure (n = 7), and dermatitis (n = 7) being most common.

CONCLUSIONS

This multicenter prospective data registry indicated that PBT for HCC gives good therapeutic effects (3-year local control rate of 90%) with a low risk of severe late adverse events.

Evolving Role of Proton Radiation Therapy in Clinical Practice

With the expansion of proton radiation therapy centers across the United States and a gradually expanding body of academic evidence supporting its use, more patients are receiving-and asking about-proton therapy than ever before. Here, we outline, for nonradiation oncologists, the theoretical benefits of proton therapy, the clinical evidence to date, the controversies affecting utilization, and the numerous randomized trials currently in progress. We also discuss the challenges of researching and delivering proton therapy, including the cost of constructing and maintaining centers, barriers with insurance approval, clinical situations in which proton therapy may be approached with caution, and the issue of equitable access for all patients. The purpose of this review is to assist practicing oncologists in understanding the evolving role of proton therapy and to help nonradiation oncologists guide patients regarding this technology.

Pushing the limits of treatment for hepatocellular carcinoma

PURPOSE OF REVIEW

We review existing and newer strategies for treatment and surveillance of hepatocellular carcinoma (HCC) both pre and postliver transplantation.

SUMMARY

HCC is rising in incidence and patients are often diagnosed at later stages. Consequently, there is a need for treatment strategies which include collaboration of multiple specialties. Combinations of locoregional, systemic, and surgical therapies are yielding better postliver transplantation (post-LT) outcomes for patients with HCC than previously seen. Tumor biology (tumor size, number, location, serum markers, response to therapy) can help identify patients who are at high risk for HCC recurrence posttransplantation and may expand transplant eligibility for some patients.

SBRT for Liver Tumors: What the Interventional Radiologist Needs to Know

This review summarizes the clinical evidence supporting the utilization of stereotactic body radiotherapy (SBRT) for liver tumors, including hepatocellular carcinoma, liver metastases, and cholangiocarcinoma. Emerging prospective evidence has demonstrated the benefit and low rates of toxicity across a broad range of clinical contexts. We provide an introduction for the interventional radiologist, with a discussion of underlying themes such as tumor dose-response, mitigation of liver toxicity, and the technical considerations relevant to performing liver SBRT. Ultimately, we recommend that SBRT should be routinely included in the armamentarium of locoregional therapies for liver malignancies, alongside those liver-directed therapies offered by interventional radiology.

Role of Stereotactic Body Radiation Therapy in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC)is a common type of liver cancer with a poor prognosis, especially in patients with advanced stages or underlying liver disease. While surgical resection, liver transplantation, and ablation therapies have traditionally been the mainstay of treatment for HCC, radiation therapy has become increasingly recognized as an effective alternative, particularly for those who are not surgical candidates. Stereotactic Body Radiation Therapy (SBRT) is a highly precise form of radiation therapy that delivers very high doses of radiation to the tumor while sparing surrounding healthy tissue. Several studies have reported favorable outcomes with SBRT in HCC treatment. Moreover, SBRT can be used to treat recurrent HCC after prior treatment, offering a potentially curative approach in select cases. While SBRT has demonstrated its efficacy and safety in treating HCC, future studies are needed to further investigate the potential role of SBRT in combination with other treatments for HCC.

Radiation and Immune Checkpoint Inhibitors: Combination Therapy for Treatment of Hepatocellular Carcinoma

The liver tumor immune microenvironment has been thought to possess a critical role in the development and progression of hepatocellular carcinoma (HCC). Despite the approval of immune checkpoint inhibitors (ICIs), such as programmed cell death receptor 1 (PD-1)/programmed cell death ligand 1 (PD-L1) and cytotoxic T lymphocyte associated protein 4 (CTLA-4) inhibitors, for several types of cancers, including HCC, liver metastases have shown evidence of resistance or poor response to immunotherapies. Radiation therapy (RT) has displayed evidence of immunosuppressive effects through the upregulation of immune checkpoint molecules post-treatment. However, it was revealed that the limitations of ICIs can be overcome through the use of RT, as it can reshape the liver immune microenvironment. Moreover, ICIs are able to overcome the RT-induced inhibitory signals, effectively restoring anti-tumor activity. Owing to the synergetic effect believed to arise from the combination of ICIs with RT, several clinical trials are currently ongoing to assess the efficacy and safety of this treatment for patients with HCC.

Proton beam radiotherapy versus transarterial chemoembolization for hepatocellular carcinoma: Results of a randomized clinical trial

BACKGROUND

This study compares survival rates, recurrence patterns, toxicity, and treatment cost in patients with hepatocellular carcinoma (HCC) treated with either transarterial chemoembolization (TACE) or proton beam radiotherapy (PBT).

METHODS

Subjects with untreated HCC meeting Milan or San Francisco transplant criteria were recruited. Subjects were randomized to receive PBT (n = 36) or TACE (n = 40). Proton therapy was administered in 15 fractions over 3 weeks to a total dose of 70.2 Gy. TACE was repeated until complete or maximal response. The primary outcome measure was overall survival (OS). Secondary end points were progression-free survival (PFS), local control (LC), toxicity, and cost.

RESULTS

Of the 76 randomized patients, 74 were assessed for outcome measures. The 2-year OS for PBT versus TACE was similar at 68%, 95% confidence interval (CI), 0.54-0.86, and 65%, 95% CI, 0.52-0.83 (p = .80), however, median PFS was improved for PBT versus TACE (not reached vs. 12 months, p = .002). LC was improved with PBT versus TACE (hazard ratio, 5.64; 95% CI, 1.78-17.9, p = .003). Days of posttreatment hospitalization were 24 for PBT and 166 for TACE (p < .001). Total mean cost per patient for treatment and posttreatment care revealed a 28% cost savings for PBT.

CONCLUSIONS

PBT and TACE yielded similar OS for treatment of HCC, but PFS and LC were improved with PBT compared to TACE. Patients treated with PBT required fewer courses of treatment, fewer posttreatment hospitalization days, and reduced cost of treatment compared to TACE. These data support the use of PBT as a viable treatment alternative to TACE for patients with HCC within transplant criteria.

Efficacy of a Second Course of Radiation for Patients With Metachronous Hepatocellular Carcinoma

PURPOSE

Liver-directed radiation therapy is an effective treatment for hepatocellular carcinoma (HCC), but metachronous lesions develop outside the irradiated field in >50% of patients. We hypothesized that irradiation of these new lesions would produce an outcome like that of patients receiving a first course (C1) of treatment.

METHODS AND MATERIALS

We included patients with HCC who received a second course (C2) of radiation therapy >1 month after C1. Toxicity was defined as Child-Pugh score increase ≥2 within 6 months posttreatment (binary model) and as the change in albumin-bilirubin during the year after treatment (longitudinal model). Overall survival (OS) and local failure (LF) were captured at the patient and lesion level, respectively; both were summarized with Kaplan-Meier estimates. Predictors of toxicity and OS were assessed using generalized linear mixed and Cox regression models, respectively.

RESULTS

Of 340 patients with HCC, 47 underwent irradiation for metachronous HCC, receiving similar prescription dose in C1/C2. Median follow-up was 17 months after C1 and 15 months after C2. Twenty-two percent of patients experienced toxicity after C1, and 25% experienced toxicity after C2. Worse baseline albumin-bilirubin predicted toxicity in both binary (odds ratio, 2.40; 95% CI, 1.46-3.94; P = .0005) and longitudinal models (P < .005). Two-year LF rate was 11.2% after C1 and 8.3% after C2; tumor dose (hazard ratio [HR], 0.982; 95% CI, 0.969-0.995; P = .007) and tumor size (HR, 1.135; 95% CI, 1.068-1.206; P < .005) predicted LF. Two-year OS was 46.0% after C1 and 42.6% after C2; tumor dose (HR, 0.986; 95% CI, 0.979-0.992; P < .005) and tumor size (HR, 1.049; 95% CI, 1.010-1.088; P = .0124) predicted OS. Reirradiation was not associated with toxicity (P > .7), LF (P = .79), or OS (P = .39).

CONCLUSIONS

In this largest series in the Western hemisphere, we demonstrate that irradiation for metachronous HCC offers low rates of LF with acceptable toxicity and OS like that of patients receiving a C1. These findings support judicious selection of patients for reirradiation in metachronous HCC.

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.

Advances and Challenges in Conducting Clinical Trials With Proton Beam Therapy

Advances in proton therapy have garnered much attention and speculation in recent years as the indications for proton therapy have grown beyond pediatric, prostate, spine, and ocular tumors. To achieve and maintain consistent access to this cancer treatment and to ensure the future viability and availability of proton centers in the United States, a call for evidence has been heard and answered by proton radiation oncologists. Answers provided in this review include the evolution of proton therapy research, rationale for proton clinical trial design, challenges in and barriers to the conduct of proton therapy research, and other unique considerations for the study of proton therapy.

Non-Surgical Locoregional Therapies Alone or in Combination with Systemic Therapy in Patients with Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the most common primary liver cancer, representing the third-leading cause of cancer-related deaths worldwide. Curative intent treatment options for patients with HCC include liver transplantation, resection and ablation of small lesions. Other potentially curative therapies include cryoablation, microwave ablation and percutaneous alcohol injection. For locally advanced disease, different arterially directed therapies including transarterial chemoembolization and selective internal radiation therapy, plus external beam radiation including three-dimensional conformal radiation therapy, intensity-modulated radiation therapy, stereotactic body radiation therapy and proton beam therapy, are available or studied. Systemic therapies based on checkpoint inhibitors and tyrosine kinase inhibitors are available for the management of metastatic HCC and sometimes for locally advanced disease. Combinations of locoregional therapies with systemic drugs are currently the subject of several clinical trials.

Recent Advances in Metal-Based NanoEnhancers for Particle Therapy

Radiotherapy is one of the most common therapeutic regimens for cancer treatment. Over the past decade, proton therapy (PT) has emerged as an advanced type of radiotherapy (RT) that uses proton beams instead of conventional photon RT. Both PT and carbon-ion beam therapy (CIBT) exhibit excellent therapeutic results because of the physical characteristics of the resulting Bragg peaks, which has been exploited for cancer treatment in medical centers worldwide. Although particle therapies show significant advantages to photon RT by minimizing the radiation damage to normal tissue after the tumors, they still cause damage to normal tissue before the tumor. Since the physical mechanisms are different from particle therapy and photon RT, efforts have been made to ameliorate these effects by combining nanomaterials and particle therapies to improve tumor targeting by concentrating the radiation effects. Metallic nanoparticles (MNPs) exhibit many unique properties, such as strong X-ray absorption cross-sections and catalytic activity, and they are considered nano-radioenhancers (NREs) for RT. In this review, we systematically summarize the putative mechanisms involved in NRE-induced radioenhancement in particle therapy and the experimental results in in vitro and in vivo models. We also discuss the potential of translating preclinical metal-based NP-enhanced particle therapy studies into clinical practice using examples of several metal-based NREs, such as SPION, Abraxane, AGuIX, and NBTXR3. Furthermore, the future challenges and development of NREs for PT are presented for clinical translation. Finally, we propose a roadmap to pursue future studies to strengthen the interplay of particle therapy and nanomedicine.

Radiotherapy for mediastinal lymphoma in breath hold using surface monitoring and nasal high flow oxygen: Clinical experiences and breath hold stability

PURPOSE

In this study we describe the clinical introduction and evaluation of radiotherapy in mediastinal lymphoma in breath hold using surface monitoring combined with nasal high flow therapy (NHFT) to prolong breath hold duration.

MATERIALS AND METHODS

11 Patients with mediastinal lymphoma were evaluated. 6 Patients received NHFT, 5 patients were treated in breath hold without NHFT. Breath hold stability as measured by a surface scanning system was evaluated, as well as internal movement based on cone beam computed tomography (CBCT) before and after treatment. Based on internal movement, margins were determined. In a parallel planning study we compared free breathing plans with breath hold plans using the determined margins.

RESULTS

Average inter breath hold stability was 0.6 mm for NHFT treatments, and 0.5 mm for non-NHFT treatments (p > 0.1). Intra breath hold stability was 0.8 vs. 0.6 mm (p > 0.1) on average. Using NHFT, average breath hold duration increased from 34 s to 60 s (p < 0.01). Residual CTV motion derived from CBCTs before and after each fraction was 2.0 mm for NHFT vs 2.2 mm for non-NHFT (p > 0.1). Combined with inter-fraction motion, a uniform mediastinal margin of 5 mm appears to be sufficient. In breath hold, mean lung dose is reduced by 2.6 Gy (p < 0.001), while mean heart dose is reduced by 2.0 Gy (p < 0.001).

CONCLUSION

Treatment of mediastinal lymphoma in breath hold is feasible and safe. The addition of NHFT approximately increases breath hold durations with a factor two while stability is maintained. By reducing breathing motion, margins can be decreased to 5 mm. A considerable dose reduction in heart, lungs, esophagus, and breasts can be achieved with this method.

Construction of a competitive electrochemical immunosensor based on sacrifice of Prussian blue and its ultrasensitive detection of alpha-fetoprotein

Effective signal amplification is a prerequisite for ultrasensitive detection by electrochemical immunosensors. For quantitative and ultrasensitive detection of alpha-fetoprotein (AFP), we designed a competitive electrochemical immunosensor and transferred the immunoreactivity from the electrode surface to the cuvette. AFP antigen was captured using AFP primary antibody (Ab₁) immobilized on magnetic nanobeads (MBs), and ZIF-8 nanomaterials attached to secondary antibody (Ab₂) were used as probes. MBs helped retain the sandwich structure in the test tube through incubation and washing steps. Then, an appropriately fixed excess of sodium ethylenediaminetetraacetic acid (EDTA) solution was added to the cuvettes, resulting in etching of Zn ions from ZIF-8 and formation of Zn-EDTA complexes. After magnetic separation, a certain amount of supernatant is added dropwise to the Prussian blue (PB)-modified electrode (GCE), and Fe ions (from PB) complex with the remaining EDTA in the supernatant, thus reducing the signal response value of PB. The higher the AFP concentration, the lower the amount of free EDTA in the supernatant, the less the destruction of PB, and therefore the higher the current. Under optimal conditions, the immunosensor achieved ultra-sensitive detection of AFP in the range of 10^-4 ng/mL-100 ng/mL with a limit of detection (LOD) as low as 0.032 pg/mL (S/N = 3). The excellent performance provides an important tool for the early screening and detection of AFP.

Study of hepatic toxicity in small liver tumors after photon or proton therapy based on factors predicting the benefits of proton

OBJECTIVES

In a previous study of hepatic toxicity, the following three factors were identified to predict the benefits of proton beam therapy (PBT) for hepatocellular carcinomas (HCCs) with a maximum diameter of ≤5 cm and Child-pugh grade A (CP-A): number of tumors (1 vs ≥2), the location of tumors (hepatic hilum or others), and the sum of the diameters of lesions. The aim of this study is to analyze the association between these three factors and hepatic toxicity.

METHODS

We retrospectively reviewed patients of CP-A treated with PBT or photon stereotactic body radiotherapy (X-ray radiotherapy, XRT) for HCC ≤5 cm. For normal liver dose, the V5, V10, V20 (volumes receiving 5, 10, and 20 Gy at least), and the mean dose was evaluated. The albumin-bilirubin (ALBI) and CP score changes from the baseline were evaluated at 3 and 6 months after treatment.

RESULTS

In 89 patients (XRT: 48, PBT: 41), those with two or three (2-3) predictive factors were higher normal liver doses than with zero or one (0-1) factor. In the PBT group, the ALBI score worsened more in patients with 2-3 factors than those with 0-1 factor, at 3 months (median: 0.26 vs 0.02, p = 0.032) and at 6 months (median: 0.35 vs 0.10, p = 0.009). The ALBI score change in the XRT group and CP score change in either modality were not significantly different in the number of predictive factors.

CONCLUSION

The predictive factor numbers predicted the ALBI score change in PBT but not in XRT.

ADVANCES IN KNOWLEDGE

This study suggest that the number of predictive factors previously identified (0-1 vs 2-3) were significantly associated with dosimetric parameters of the normal liver in both modalities. In the proton group, the number of predictive factors was associated with a worsening ALBI score at 3 and 6 months, but these associations were not found in the photon SBRT group.

Predictive Model of Liver Toxicity to Aid the Personalized Selection of Proton Versus Photon Therapy in Hepatocellular Carcinoma

PURPOSE

Our objective was to develop an externally validated model for predicting liver toxicity after radiation therapy in patients with hepatocellular carcinoma (HCC) that can integrate both photon and proton dose distributions with patient-specific characteristics.

METHODS AND MATERIALS

Training data consisted of all patients with HCC treated between 2008 and 2019 at our institution (n = 117, 60%/40% photon/proton). We developed a shallow convolutional neural network (CNN) to predict posttreatment liver dysfunction from the differential dose-volume histogram (DVH) and baseline liver metrics. To reduce bias and improve robustness, we used ensemble learning (CNNE). After a preregistered study analysis plan, we evaluated stability using internal bootstrap resampling and generalizability using a data set from a different institution (n = 88). Finally, we implemented a class activation map method to characterize the critical DVH subregions and benchmarked the model against logistic regression and XGBoost. The models were evaluated using the area under the receiver operating characteristic curve and area under the precision-recall curve.

RESULTS

The CNNE model showed similar internal performance and robustness compared with the benchmarks. CNNE exceeded the benchmark models in external validation, with an area under the receiver operating characteristic curve of 0.78 versus 0.55 to 0.70, and an area under the precision-recall curve of 0.6 versus 0.43 to 0.52. The model showed improved predictive power in the photon group, excellent specificity in both modalities, and high sensitivity in the photon high-risk group. Models built solely on DVHs confirm outperformance of the CNNE and indicate that the proposed structure efficiently abstracts features from both proton and photon dose distributions. The activation map method demonstrates the importance of the low-dose bath and its interaction with low liver function at baseline.

CONCLUSIONS

We developed and externally validated a patient-specific prediction model for hepatic toxicity based on the entire DVH and clinical factors that can integrate both photon and proton therapy cohorts. This model complements the new American Society for Radiation Oncology clinical practice guidelines and could support value-driven integration of proton therapy into the management of HCC.

Changes in Nutritional Status of Cancer Patients Undergoing Proton Radiation Therapy Based on Real-World Data

Methods

Observational study on 47 adult hospitalized cancer patients including 27 males and 20 females who received proton beam radiotherapy during December 2021 and August 2022. Nutritional assessments, 24 h dietary survey, handgrip strength (HGS) test, anthropometrical measurements, and hematological parameters were conducted or collected at the beginning and the completion of treatment.

Results

The rate of nutritional risk and malnutrition among the total of 47 enrolled patients was 4.3% and 12.8% at the onset of proton radiation and raised up to 6.4% and 27.7% at the end of the treatment. 42.6% of patients experienced weight loss during the proton radiotherapy, and 1 of them had weight loss over 5%, and in general, the average body weight was stable over radiotherapy. The changes in patients' 24 h dietary intakes, HGS, and anthropometrical parameters, including triceps skinfold thickness (TSF), midupper arm circumference (MUAC), and midupper arm muscle circumference (MAMC), were statistically insignificant over the treatment (all p values > 0.05). The changes in patients' hematological parameters, including total protein (TP) and serum albumin (ALB), were not statistically significant over the treatment (all p values >0.05), and the level of hemoglobin (HGB) at the end of treatment was higher than that at the onset (p < 0.05).

Conclusion

The results of this study demonstrated that proton radiotherapy might have a lighter effect on the nutritional status of cancer patients.

Proton Beam Therapy and Photon-Based Magnetic Resonance Image-Guided Radiation Therapy: The Next Frontiers of Radiation Therapy for Hepatocellular Carcinoma

External beam radiation therapy (EBRT) has increasingly been utilized in the treatment of hepatocellular carcinoma (HCC) due to technological advances with positive clinical outcomes. Innovations in EBRT include improved image guidance, motion management, treatment planning, and highly conformal techniques such as intensity-modulated radiation therapy (IMRT) and stereotactic body radiation therapy (SBRT). Moreover, proton beam therapy (PBT) and magnetic resonance image-guided radiation therapy (MRgRT) have expanded the capabilities of EBRT. PBT offers the advantage of minimizing low- and moderate-dose radiation to the surrounding normal tissue, thereby preserving uninvolved liver and allowing for dose escalation. MRgRT provides the advantage of improved soft tissue delineation compared to computerized tomography (CT) guidance. Additionally, MRgRT with online adaptive therapy is particularly useful for addressing motion not otherwise managed and reducing high-dose radiation to the normal tissue such as the stomach and bowel. PBT and online adaptive MRgRT are emerging technological advancements in EBRT that may provide a significant clinical benefit for patients with HCC.

Particle Therapy: Clinical Applications and Biological Effects

Particle therapy is a developing area of radiotherapy, mostly involving the use of protons, neutrons and carbon ions for cancer treatment. The reduction of side effects on healthy tissues in the peritumoral area is an important advantage of particle therapy. In this review, we analyze state-of-the-art particle therapy, as compared to conventional photon therapy, to identify clinical benefits and specify the mechanisms of action on tumor cells. Systematization of published data on particle therapy confirms its successful application in a wide range of cancers and reveals a variety of biological effects which manifest at the molecular level and produce the particle therapy-specific molecular signatures. Given the rapid progress in the field, the use of particle therapy holds great promise for the near future.

Radiotherapy Side Effects: Comprehensive Proteomic Study Unraveled Neural Stem Cell Degenerative Differentiation upon Ionizing Radiation

Cranial radiation therapy is one of the most effective treatments for childhood brain cancers. Despite the ameliorated survival rate of juvenile patients, radiation exposure-induced brain neurogenic region injury could markedly impair patients' cognitive functions and even their quality of life. Determining the mechanism underlying neural stem cells (NSCs) response to irradiation stress is a crucial therapeutic strategy for cognitive impairment. The present study demonstrated that X-ray irradiation arrested NSCs' cell cycle and impacted cell differentiation. To further characterize irradiation-induced molecular alterations in NSCs, two-dimensional high-resolution mass spectrometry-based quantitative proteomics analyses were conducted to explore the mechanism underlying ionizing radiation's influence on stem cell differentiation. We observed that ionizing radiation suppressed intracellular protein transport, neuron projection development, etc., particularly in differentiated cells. Redox proteomics was performed for the quantification of cysteine thiol modifications in order to profile the oxidation-reduction status of proteins in stem cells that underwent ionizing radiation treatment. Via conjoint screening of protein expression abundance and redox status datasets, several significantly expressed and oxidized proteins were identified in differentiating NSCs subjected to X-ray irradiation. Among these proteins, succinate dehydrogenase [ubiquinone] flavoprotein subunit, mitochondrial (sdha) and the acyl carrier protein, mitochondrial (Ndufab1) were highly related to neurodegenerative diseases such as Parkinson's disease, Alzheimer's disease, and Huntington's disease, illustrating the dual-character of NSCs in cell differentiation: following exposure to ionizing radiation, the normal differentiation of NSCs was compromised, and the upregulated oxidized proteins implied a degenerative differentiation trajectory. These findings could be integrated into research on neurodegenerative diseases and future preventive strategies.

Outcomes and toxicities after proton partial breast radiotherapy for early stage, hormone receptor positive breast cancer: 3-Year results of a phase II multi-center trial

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Proton therapy is a good treatment option for partial breast irradiation.

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Proton PBI results in excellent local tumor control and OAR sparing.

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Cosmesis and quality of life with PBT are comparable to other PBI modalities.

Purpose

Proton therapy (PT) for partial breast irradiation (PBI) in early-stage breast cancer can decrease morbidity versus photon PBI with superior organs-at-risk sparing. We report 3-year outcomes of the first prospective, multicenter, phase II trial of proton PBI.

Methods and Materials

This Proton Collaborative Group phase II trial (PCG BRE007-12) recruited women ≥ 50 years with node-negative, estrogen receptor (ER)-positive, ≤3cm, invasive ductal carcinoma (IDC) or ductal carcinoma in situ undergoing breast conserving surgery followed by proton PBI (40 Gy(RBE), 10 daily fractions). Primary endpoint was freedom from ipsilateral breast cancer recurrence. Adverse events were prospectively graded using CTCAEv4.0. Breast Cancer Treatment Outcome Scale (BCTOS) assessed patient-reported quality of life (PRQOL).

Results

Thirty-eight evaluable patients enrolled between 2/2013–11/2016. Median age was 67 years (range 50–79); 55 % had left-sided disease, and median tumor size was 0.9 cm. Treatment was delivered in ≥ 2 fields predominantly with uniform scanning PT (n = 37). At 35-month median follow-up (12–62), all patients were alive, and none had local, regional or distant disease progression. One patient developed an ER-negative contralateral IDC. Seven grade 2 adverse events occurred; no radiotherapy-related grade ≥ 3 toxicities occurred. Changes in BCTOS subdomain mean scores were maximum 0.36, indicating no meaningful change in PRQOL. Median heart volume receiving 5 Gy (V5Gy), lung V20Gy, and lung V10Gy were 0 %, 0 % and 0.19 %, respectively.

Conclusion

At 3 years, proton PBI provided 100 % cancer control for early-stage, ER-positive breast cancer. Toxicities are minimal, and PRQOL remains acceptable with continued follow-up. These findings support PT as a safe and effective PBI delivery option.

Imaging Features in the Liver after Stereotactic Body Radiation Therapy

Historically, radiation therapy was not considered in treatment of liver tumors owing to the risk of radiation-induced liver disease. However, development of highly conformed radiation treatments such as stereotactic body radiation therapy (SBRT) has increased use of radiation therapy in the liver. SBRT is indicated in treatment of primary and metastatic liver tumors with outcomes comparable to those of other local therapies, especially in treatment of hepatocellular carcinoma. After SBRT, imaging features of the tumor and surrounding background hepatic parenchyma demonstrate a predictable pattern immediately after treatment and during follow-up. The goals of SBRT are to deliver a lethal radiation dose to the targeted liver tumor and to minimize radiation dose to normal liver parenchyma and other adjacent organs. Evaluation of tumor response after SBRT centers on changes in size and enhancement; however, these changes are often delayed secondary to the underlying physiologic effects of radiation. Knowledge of the underlying pathophysiologic mechanisms of SBRT should allow better understanding of the typical imaging features in detection of tumor response and avoid misinterpretation from common pitfalls and atypical imaging findings. Imaging features of radiation-induced change in the surrounding liver parenchyma are characterized by a focal liver reaction that can potentially be mistaken for no response or recurrence of tumor. Knowledge of the pattern and chronology of this phenomenon may allay any uncertainty in assessment of tumor response. Other pitfalls related to fiducial marker placement or combination therapies are important to recognize. The authors review the basic principles of SBRT and illustrate post-SBRT imaging features of treated liver tumors and adjacent liver parenchyma with a focus on avoiding pitfalls in imaging evaluation of response. Online supplemental material is available for this article. ^©RSNA, 2022.

The American Brachytherapy Society consensus statement for permanent implant brachytherapy using Yttrium-90 microsphere radioembolization for liver tumors

PURPOSE

To develop a multidisciplinary consensus for high quality multidisciplinary implementation of brachytherapy using Yttrium-90 (90Y) microspheres transarterial radioembolization (90Y TARE) for primary and metastatic cancers in the liver.

METHODS AND MATERIALS

Members of the American Brachytherapy Society (ABS) and colleagues with multidisciplinary expertise in liver tumor therapy formulated guidelines for 90Y TARE for unresectable primary liver malignancies and unresectable metastatic cancer to the liver. The consensus is provided on the most recent literature and clinical experience.

RESULTS

The ABS strongly recommends the use of 90Y microsphere brachytherapy for the definitive/palliative treatment of unresectable liver cancer when recommended by the multidisciplinary team. A quality management program must be implemented at the start of 90Y TARE program development and follow-up data should be tracked for efficacy and toxicity. Patient-specific dosimetry optimized for treatment intent is recommended when conducting 90Y TARE. Implementation in patients on systemic therapy should account for factors that may enhance treatment related toxicity without delaying treatment inappropriately. Further management and salvage therapy options including retreatment with 90Y TARE should be carefully considered.

CONCLUSIONS

ABS consensus for implementing a safe 90Y TARE program for liver cancer in the multidisciplinary setting is presented. It builds on previous guidelines to include recommendations for appropriate implementation based on current literature and practices in experienced centers. Practitioners and cooperative groups are encouraged to use this document as a guide to formulate their clinical practices and to adopt the most recent dose reporting policies that are critical for a unified outcome analysis of future effectiveness studies.

Proton therapy in the treatment of hepatocellular carcinoma

Liver cancer represents one of the most common causes of death from cancer worldwide. Hepatocellular carcinoma (HCC) accounts for 90% of all primary liver cancers. Among local therapies, evidence regarding the use of radiation therapy is growing. Proton therapy currently represents the most advanced radiation therapy technique with unique physical properties which fit well with liver irradiation. Here, in this review, we aim to 1) illustrate the rationale for the use of proton therapy (PT) in the treatment of HCC, 2) discuss the technical challenges of advanced PT in this disease, 3) review the major clinical studies regarding the use of PT for HCC, and 4) analyze the potential developments and future directions of PT in this setting.

A study on predicting cases that would benefit from proton beam therapy in primary liver tumors of less than or equal to 5 cm based on the estimated incidence of hepatic toxicity

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An advantage of PBT is reducing the liver receiving low doses of radiation.

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The factors predicting the benefit in PBT are different among NTCP models.

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The tumor size, number, and location are useful in estimating the benefits of PBT.

Background

Materials and methods

Results

Conclusions

Proton Therapy in the Management of Hepatocellular Carcinoma

Simple Summary

Radiation therapy is among the locoregional therapy modalities used to treat unresectable or medically inoperable hepatocellular carcinoma (HCC). Proton radiation therapy plays a major role in the treatment of HCC, especially when liver toxicity is a concern. The aim of this review is to provide a concise and comprehensive summary on the use of proton therapy in the management of HCC.

Abstract

Proton radiation therapy plays a central role in the treatment of hepatocellular carcinoma (HCC). Because of the near-zero exit dose and improved sparing of normal liver parenchyma, protons are being used even in challenging scenarios, including larger or multifocal liver tumors, and those associated with vascular tumor thrombus. There is a mounting level of evidence that suggests that protons are superior to photons in terms of survival and toxicity outcomes, specifically the progression to liver failure. A randomized controlled trial comparing protons to photons is currently underway to verify this hypothesis.

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.

Radiofrequency ablation vs radiation therapy vs transarterial chemoembolization vs yttrium 90 for local treatment of liver cancer - a systematic review and network meta-analysis of survival data

INTRODUCTION

The comparative effectiveness of radiofrequency ablation (RFA), radiation therapy (RT), transarterial chemoembolization (TACE) and transarterial radioembolization with Yttrium-90 (Y90) relative to one another for the treatment of hepatocellular carcinoma (HCC) is unclear. The aim of this systematic review and network meta-analysis is to compare RFA to RT to TACE to Y90 in the treatment of HCC.

METHODS

Pubmed, Embase and Cochrane CENTRAL were searched up until April 19, 2021. Observational analyses with propensity score matched (PSM) cohort analyses and randomized controlled trials (RCT) reporting on two or more treatments relative to one another with respect to overall survival (OS) and/or progression free survival (PFS) were included. Survival data were extracted from Kaplan-Meier survival curves, and meta-analyzed using a multivariate network meta-analysis.

RESULTS

After exclusions, 24 RCTs or PSM observational studies reporting on 5549 patients were included. While 1-year OS was greater for Y90 than TACE (RR 0.85, 95% CI: 0.72-0.99), all other 1-year OS comparisons across the 4 modalities yielded similar OS, and there were no differences across any modalities in 2-year and 3-year OS. TACE had a modest PFS advantage relative to RFA (RR 0.81, 95% CI: 0.68-0.95) and RT (RR 0.65, 95% CI: 0.51-0.83) at 2 years.

CONCLUSION

All modalities assessed resulted in similar OS, which explains the current heterogenous practice patterns. This conclusion may assist in decision making based on administrative and patient costs, and implementation of these modalities. Other factors such as toxicity rate specific to individual patients could not be assessed using network meta-analysis and may also play a role in selection of modality. Further studies, ideally using PSM cohort analyses or RCT study design, reporting on OS, PFS, local control, complete response and toxicity are needed prior to drawing definitive conclusions.

Proton Beam Therapy in Managing Unresectable Hepatocellular Carcinoma with Bile Duct Invasion

Hepatocellular carcinoma (HCC) with bile duct invasion is a rare and notorious subtype of HCC. This study included patients that had unresectable HCC with bile duct invasion and proton beam therapy between November 2015 and February 2021. Twenty patients fit the inclusion criteria. The median tumor size was 6.3 cm. Nine patients (45.0%) had major vascular invasions. All included patients received the radiation dose of 72.6 gray relative biological effectiveness due to the proximity of porta hepatis and tumor. The median follow-up time was 19.9 months. The median overall survival was 19.9 months among deceased patients. The 1-year cumulative local recurrence rates were 5.3%, with only two patients developing in-field failure. The 1-year and 2-year overall survival rates were 79.4% and 53.3%. The 1-year progression-free survival was 58.9%. Four patients developed radiation-induced liver disease. The 1-year cholangitis-free survival was 55.0%. Skin toxicity was the most common acute toxicity and rarely severe. Eight patients developed ≤ grade 3 gastrointestinal ulcers. Proton beam therapy offers desirable survival outcomes for unresectable HCC patients with bile duct invasion. Optimal local tumor control could also be obtained within acceptable toxicities.

Mathematical Modeling to Simulate the Effect of Adding Radiation Therapy to Immunotherapy and Application to Hepatocellular Carcinoma

PURPOSE

To develop a comprehensive framework to simulate the response to immune checkpoint inhibitors (ICIs) in combination with radiation therapy (RT) and to apply the framework for investigating ICI-RT combination regimen in patients with hepatocellular carcinoma (HCC).

METHODS AND MATERIALS

The mechanistic mathematical model is based on dynamic biological interactions between the immune system and the tumor using input data from patient blood samples and outcomes of clinical trials. The cell compartments are described by ordinary differential equations and represent irradiated and nonirradiated tumor cells and lymphocytes. The effect of ICI is modeled using an immune activation term that is based on tumor size changes observed in a phase 1/2 clinical trial for HCC. Simulated combination regimen are based on ongoing ICI-RT trials.

RESULTS

The proposed framework successfully describes tumor volume trajectories observed in early-stage clinical trials of durvalumab monotherapy in patients with HCC. For ICI-RT treatment regimen the irradiated tumor fraction is the most important parameter for the efficacy. For 90% of the tumor cells being irradiated, adding RT to ICI yields an increase in clinical benefit from 33% to 71% in nonirradiated tumor sites. The model agrees with clinical data showing an association of outcome with initial tumor volume and lymphocyte counts. We demonstrate model application in clinical trial design to predict progression-free survival curves, showing that the cohort size to show significant improvement heavily depends on the irradiated tumor fraction.

CONCLUSIONS

We present a framework extending radiation cell kill models to include circulating lymphocytes and the effect of ICIs and enable simulation of combination strategies. The simulations predict that a significant amount of the benefit from RT in combination with ICI stems from the reduction in irradiated tumor burden and associated immune suppression. This aspect needs to be included in the interpretation of outcomes and the design of novel combination trials.

Neoadjuvant approaches in hepatocellular carcinoma: There's no time like the present

Hepatocellular carcinoma remains a lethal malignancy and is an increasingly common cause of cancer death worldwide. Curative-intent surgical resection remains the standard of care for eligible patients, yet outcomes remain poor for many patients, with most patients experiencing recurrence in the five years after resection. There is currently significant interest in utilizing locoregional and systemic therapies - in both the neoadjuvant and adjuvant settings - to increase the chance of cure. This review article appraises the existing literature and current clinical trial landscape of neoadjuvant therapies in hepatocellular carcinoma.

Proton therapy for prostate cancer: current state and future perspectives

OBJECTIVE

Localized prostate cancer can be treated with several radiotherapeutic approaches. Proton therapy (PT) can precisely target tumors, thus sparing normal tissues and reducing side-effects without sacrificing cancer control. However, PT is a costly treatment compared with conventional photon radiotherapy, which may undermine its overall efficacy. In this review, we summarize current data on the dosimetric rationale, clinical benefits, and cost of PT for prostate cancer.

METHODS

An extensive literature review of PT for prostate cancer was performed with emphasis on studies investigating dosimetric advantage, clinical outcomes, cost-effective strategies, and novel technology trends.

RESULTS

PT is safe, and its efficacy is comparable to that of standard photon-based therapy or brachytherapy. Data on gastrointestinal, genitourinary, and sexual function toxicity profiles are conflicting; however, PT is associated with a low risk of second cancer and has no effects on testosterone levels. Regarding cost-effectiveness, PT is suboptimal, although evolving trends in radiation delivery and construction of PT centers may help reduce the cost.

CONCLUSION

PT has several advantages over conventional photon radiotherapy, and novel approaches may increase its efficacy and safety. Large prospective randomized trials comparing photon therapy with proton-based treatments are ongoing and may provide data on the differences in efficacy, toxicity profile, and quality of life between proton- and photon-based treatments for prostate cancer in the modern era.

ADVANCES IN KNOWLEDGE

PT provides excellent physical advantages and has a superior dose profile compared with X-ray radiotherapy. Further evidence from clinical trials and research studies will clarify the role of PT in the treatment of prostate cancer, and facilitate the implementation of PT in a more accessible, affordable, efficient, and safe way.

Will the collaboration of surgery and external radiotherapy open new avenues for hepatocellular carcinoma with portal vein thrombosis?

Portal invasion of hepatocellular carcinoma (HCC) occurs in 12.5%-40% of patients diagnosed with cancer and yields poor clinical outcomes. Since it is a common cause of inoperability, sorafenib was regarded as the standard treatment for HCC in the Barcelona Clinic of Liver Cancer guidelines. However, the median survival of the Asian population was only approximately 6 mo, and the tumor response rate was less than moderate (< 5%). Various locoregional modalities were performed, including external beam radiotherapy (EBRT), transarterial chemoembolization, hepatic arterial infusion chemotherapy, and surgery, alone or in combination. Among them, EBRT is a noninvasive method and can safely treat tumors involving the major vessels. Palliative EBRT has been commonly performed, especially in East Asian countries, where locally invasive HCC is highly prevalent. Although surgery is not commonly indicated, pioneering studies have demonstrated encouraging results in recent decades. Furthermore, the combination of neo- or adjuvant EBRT and surgery has been recently used and has significantly improved the outcomes of HCC patients, as reported in a few randomized studies. Regarding systemic modality, a combination of novel immunotherapy and vascular endothelial growth factor inhibitor showed results superior to that of sorafenib as a first-line agent. Future clinical trials investigating the combined use of these novel agents, surgery, and EBRT are expected to improve the prognosis of HCC with portal invasion.

Predictive Modeling of Survival and Toxicity in Patients With Hepatocellular Carcinoma After Radiotherapy

PURPOSE

To stratify patients and aid clinical decision making, we developed machine learning models to predict treatment failure and radiation-induced toxicities after radiotherapy (RT) in patients with hepatocellular carcinoma across institutions.

MATERIALS AND METHODS

The models were developed using linear and nonlinear algorithms, predicting survival, nonlocal failure, radiation-induced liver disease, and lymphopenia from baseline patient and treatment parameters. The models were trained on 207 patients from Massachusetts General Hospital. Performance was quantified using Harrell's c-index, area under the curve (AUC), and accuracy in high-risk populations. Models' structures were optimized in a nested cross-validation approach to prevent overfitting. A study analysis plan was registered before external validation using 143 patients from MD Anderson Cancer Center. Clinical utility was assessed using net-benefit analysis.

RESULTS

The survival model stratified high-risk versus low-risk patients well in the external validation cohort (c-index = 0.75), better than existing risk scores. Predictions of 1-year survival and nonlocal failure were excellent (external AUC = 0.74 and 0.80, respectively), especially in the high-risk group (accuracy > 90%). Cause-of-death analysis showed differential modes of treatment failure in these cohorts and indicated that these models could be used to stratify RT patients for liver-sparing treatment regimen or combination approaches with systemic agents. Predictions of liver disease and lymphopenia were good but less robust (external AUC = 0.68 and 0.7, respectively), suggesting the need for more comprehensive consideration of dosimetry and better predictive biomarkers. The liver disease model showed excellent accuracy in the high-risk group (92%) and revealed possible interactions of platelet count with initial liver function.

CONCLUSION

Machine learning approaches can provide reliable outcome predictions in patients with hepatocellular carcinoma after RT in diverse cohorts across institutions. The excellent performance, particularly in high-risk patients, suggests novel strategies for patient stratification and treatment selection.

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.

Clinical application of advances and innovation in radiation treatment of hepatocellular carcinoma

Background:

Hepatocellular carcinoma (HCC) management has evolved over the past two decades, with the development of newer treatment modalities. While various options are available, unmet needs are reflected through the mixed treatment outcome for intermediate-stage HCC. As HCC is radiosensitive, radiation therapies have a significant role in management. Radiation therapies offer local control for unresectable lesions and for patients who are not surgical candidates. Radiotherapy also provides palliation in metastatic disease, and acts as a bridge to resection and transplantation in selected patients. Advancements in radiotherapy modalities offer improved dose planning and targeted delivery, allowing for better tumor response and safer dose escalations while minimizing the risks of radiation-induced liver damage. Radiotherapy modalities are broadly classified into external beam radiation therapy and selective internal radiation therapy. With emerging modalities, radiotherapy plays a complementary role in the multidisciplinary care of HCC patients.

Aim:

We aim to provide an overview of the role and clinical application of radiation therapies in HCC management.

Relevance for Patients:

The continuous evolution of radiotherapy techniques allows for improved therapeutic outcomes while mitigating unwanted adverse effects, making it an attractive modality in HCC management. Rigorous clinical studies, quality research and comprehensive datasets will further its application in the present era of evidence-based practice in Medicine.

Stereotactic body radiation therapy for primary liver tumors: An effective liver-directed therapy in the toolbox

The use of radiation for primary liver cancers has historically been limited because of the risk of radiation-induced liver disease. Treatment fields have become more conformal because of several technical advances, and this has allowed for dose escalation. Stereotactic body radiation therapy (SBRT), also known as stereotactic ablative radiotherapy, is now able to safely treat liver tumors to ablative doses while sparing functional liver parenchyma by using highly conformal therapy. Several retrospective and small prospective studies have examined the use of SBRT for liver cancers; however, there is a lack of well-powered randomized studies to definitively guide management in these settings. Recent advances in systemic therapy for primary liver cancers have improved outcomes; however, the optimal selection criteria for SBRT as a local therapy remain unclear among other liver-directed options such as radiofrequency ablation, transarterial chemoembolization, and radioembolization.

Carbon Ion Radiotherapy in the Management of Hepatocellular Carcinoma

Localized hepatocellular carcinoma (HCC) that is unresectable and non-transplantable can be treated by several liver-directed therapies. External beam radiation therapy (EBRT) is an increasingly accepted and widely utilized treatment modality in this setting. Accelerated charged particles such as proton beam therapy (PBT) and carbon ion radiation therapy (CIRT) offer technological advancements over conventional photon radiotherapy. In this review, we summarize the distinct advantages of CIRT use for HCC treatment, focusing on physical and biological attributes, and outline dosimetric and treatment planning caveats. Based on these considerations, we posit that HCC may be among the best indications for use of CIRT, as it allows for maximizing tumoricidal doses to the target volume while minimizing the dose to the organs at risk.

Intensity Modulated Proton Therapy for Hepatocellular Carcinoma: Initial Clinical Experience

Purpose

Our purpose was to assess the safety and efficacy of intensity modulated proton therapy (IMPT) for the treatment of hepatocellular carcinoma (HCC).

Methods and Materials

A retrospective review was conducted on all patients who were treated with IMPT for HCC with curative intent from June 2015 to December 2018. All patients had fiducials placed before treatment. Inverse treatment planning used robust optimization with 2 to 3 beams. The majority of patients were treated in 15 fractions (n = 30, 81%, 52.5-67.5 Gy, relative biological effectiveness), whereas the remainder were treated in 5 fractions (n = 7, 19%, 37.5-50 Gy, relative biological effectiveness). Daily image guidance consisted of orthogonal kilovoltage x-rays and use of a 6° of freedom robotic couch. Outcomes (local control, progression free survival, and overall survival) were determined using Kaplan-Meier methods.

Results

Thirty-seven patients were included. The median follow-up for living patients was 21 months (Q1-Q3, 17-30 months). Pretreatment Child-Pugh score was A5-6 in 70% of patients and B7-9 in 30% of patients. Nineteen patients had prior liver directed therapy for HCC before IMPT. Eight patients (22%) required a replan during treatment, most commonly due to inadequate clinical target volume coverage. One patient (3%) experienced a grade 3 acute toxicity (pain) with no recorded grade 4 or 5 toxicities. An increase in Child-Pugh score by ≥ 2 within 3 months of treatment was observed in 6 patients (16%). At 1 year, local control was 94%, intrahepatic control was 54%, progression free survival was 35%, and overall survival was 78%.

Conclusions

IMPT is safe and feasible for treatment of HCC.

Frontiers of therapy for hepatocellular carcinoma

The incidence of hepatocellular carcinoma continues to increase worldwide. Fortunately, there have been notable recent advances in locoregional and systemic therapy. In this current review, we will highlight these new developments and future directions of hepatocellular carcinoma treatment and address the importance of a multidisciplinary approach to treatment.

SBRT for HCC: Overview of technique and treatment response assessment

Stereotactic body radiation therapy (SBRT) is an emerging locoregional treatment (LRT) modality used in the management of patients with hepatocellular carcinoma (HCC). The decision to treat HCC with LRT is evaluated in a multidisciplinary setting, and the specific LRT chosen depends on the treatment intent, such as bridge-to-transplant, down-staging to transplant, definitive/curative treatment, and/or palliation, as well as underlying patient clinical factors. Accurate assessment of treatment response is necessary in order to guide clinical management in these patients. Patients who undergo LRT need continuous imaging evaluation to assess treatment response and to evaluate for recurrence. Thus, an accurate understanding of expected post-SBRT imaging findings is critical to avoid misinterpreting normal post-treatment changes as local progression or viable tumor. SBRT-treated HCC demonstrates unique imaging findings that differ from HCC treated with other forms of LRT. In particular, SBRT-treated HCC can demonstrate persistent APHE and washout on short-term follow-up imaging. This brief review summarizes current evidence for the use of SBRT for HCC, including patient population, SBRT technique and procedure, tumor response assessment on contrast-enhanced cross-sectional imaging with expected findings, and pitfalls in treatment response evaluation.

Reduce Patient Treatment wait time in a Proton Beam Facility - A Gatekeeper Approach

Patient wait time can negatively impact treatment quality in a proton therapy center, where multiple treatment rooms share one proton beam. Wait time increases patient discomfort that can lead to patient motion, dissatisfaction, and longer treatment delay. This study was to develop a patient call-back model that reduced patient wait while efficiently utilizing the proton beam. A "Gatekeeper" logic allowing therapists to adjust the time of a patient's call-back to the treatment room was developed. It uses a two-pronged approach to minimize overlap of long treatment and the possibility of excessive wait in the queue to receive the proton beam. The goal was to reduce the maximum wait time to less than eight minutes per field for a four-room facility. The effectiveness of this logic was evaluated through simulation, and five scenarios were compared. Four scenarios implementing various levels of gatekeeper logic were compared with the original scenario without the logic. The best performing model provided a reduction of the maximum field wait by 26% and met the predefined goal. Adjusting call-back extended the treatment day length by an average of 6 min and a maximum of 12 min in total. The use of this gatekeeper logic significantly reduces patient field wait with minimal impact on treatment day length for a four-room proton facility. A sample interface that adopts this logic for therapists to make informed decision on patient call-back time is demonstrated.

Long-term clinical outcomes of patients receiving proton beam therapy for caudate lobe hepatocellular carcinoma

Hepatocellular carcinoma (HCC) located in the caudate lobe (caudate HCC) is rare; however, patients with this type of tumour have poorer prognoses than those with HCC in other segments. Despite many published reports on the clinical usefulness of proton beam therapy (PBT) for HCC, data on the clinical outcomes of patients undergoing PBT for caudate HCC remain scarce. Therefore, the present study aimed to investigate the outcomes of this group of patients. Thirty patients with caudate HCC who underwent definitive PBT between February 2002 and February 2014 were retrospectively analysed. The total irradiation doses ranged from 55 to 77 (median 72.6) Gy relative biological dose. The median follow-up period was 37.5 (range, 3.0-152.0) months. The overall survival (OS) rates at one, three and five years were 86.6%, 62.8% and 46.1%, respectively. According to univariate and multivariate analyses, Child-Pugh A (P < 0.01), having a single tumour (P = 0.02) and a low serum alpha-fetoprotein level (AFP; P < 0.01) were significant factors predicting longer survival. The local control (LC) rates at one, three and five years were 100%, 85.9% and 85.9%, respectively, while the corresponding progression-free survival (PFS) rates were 65%, 27.5% and 22%, respectively. No grade 3 or worse adverse events were observed. PBT is effective and safe for the treatment of caudate HCC, and should therefore be considered a feasible option for intervention in patients with this disease.

Contemporary radiotherapy: present and future

Oncology care is increasingly a multidisciplinary endeavour, and radiation therapy continues to have a key role across the disease spectrum in nearly every cancer. However, the field of radiation oncology is still one of the most poorly understood of the cancer disciplines. In this Review, we attempt to summarise and contextualise developments within the field of radiation oncology for the non-radiation oncologist. We discuss advancements in treatment technologies and imaging, followed by an overview of the interplay with advancements in systemic therapy and surgical techniques. Finally, we review new frontiers in radiation oncology, including advances within the metastatic disease continuum, reirradiation, and emerging types of radiation therapy.

Who Will Benefit from Charged-Particle Therapy?

Charged-particle therapy (CPT) such as proton beam therapy (PBT) and carbon-ion radiotherapy (CIRT) exhibit substantial physical and biological advantages compared to conventional photon radiotherapy. As it can reduce the amount of radiation irradiated in the normal organ, CPT has been mainly applied to pediatric cancer and radioresistent tumors in the eloquent area. Although there is a possibility of greater benefits, high set-up cost and dearth of high level of clinical evidence hinder wide applications of CPT. This review aims to present recent clinical results of PBT and CIRT in selected diseases focusing on possible indications of CPT. We also discussed how clinical studies are conducted to increase the number of patients who can benefit from CPT despite its high cost.