Unresectable solitary hepatocellular carcinoma not amenable to radiofrequency ablation: multicenter radiology-pathology correlation and survival of radiation segmentectomy

Prediction of hepatocellular carcinoma response to radiation segmentectomy using an MRI-based machine learning approach

PURPOSE

To evaluate the value of pre-treatment MRI-based radiomics in patients with hepatocellular carcinoma (HCC) for the prediction of response to Yttrium 90 radiation segmentectomy.

METHODS

This retrospective study included 154 patients (38 female; mean age 66.8 years) who underwent contrast-enhanced MRI prior to radiation segmentectomy. Radiomics features were manually extracted on volumes of interest on post-contrast T1-weighted images at the portal venous phase (PVP). Tumor-based response assessment was evaluated 6 months post-treatment using mRECIST. A logistic regression model was used to predict binary response outcome [complete response at 6 months with no-re-treatment (response group) against the rest (non-response group, including partial response, progressive disease, stable disease and complete response after re-treatment within 6 months after radiation segmentectomy) using baseline clinical parameters and radiomics features. We accessed the value of different sets of predictors using cross-validation technique. AUCs were compared using DeLong tests.

RESULTS

A total 168 HCCs (mean size 2.9 ± 1.7 cm) were analyzed in 154 patients. The response group consisted of 113 HCCs and the non-response group of 55 HCCs. Baseline clinical parameters (AUC 0.531; sensitivity, 0.781; specificity, 0.279; positive predictive value (PPV), 0.345; negative predictive value (NPV), 0.724) and AFP (AUC 0.632; sensitivity, 0.833; specificity, 0.466; PPV, 0.432; NPV, 0.851) showed poor performance for response prediction. The model using a combination of radiomics features and clinical parameters/AFP showed the best performance (AUC 0.736; sensitivity, 0.706; specificity, 0.662; PPV 0.504; NPV, 0.822), significantly better than the clinical model (p < 0.001) or AFP alone (p < 0.001).

CONCLUSION

The combination of radiomics features from pre-treatment MRI with clinical parameters and AFP showed fair performance for predicting HCC response to radiation segmentectomy, better than that of AFP. These results need further validation.

Advances and Emerging Techniques in Y-90 Radioembolization for Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the fourth leading cause of cancer deaths worldwide. Despite the high incidence of HCC, mortality remains high, with an estimated 5-year survival rate of less than 20%. Surgical resection represents a potential curative treatment for HCC; however, less than 20% of patients with HCC are candidates for surgical resection. In patients with unresectable HCC, Yttrium-90 (Y90) transarterial radioembolization (TARE) has emerged as an innovative treatment option. This locoregional therapy delivers high doses of radiation directly to liver tumors via intra-arterial injection, allowing for the targeted destruction of malignant cells while sparing surrounding healthy tissue. In this review, we will explore the latest advances in Y90 TARE for the treatment of HCC, focusing on key developments such as the following: (1) improvements in radiation lobectomy and segmentectomy techniques, (2) the introduction of personalized dosimetry, (3) the integration of combination therapies, (4) the use of imageable microspheres, (5) pressure-enabled Y90 delivery systems, and (6) the application of Y90 surrogates.

Radiation Segmentectomy and Modified Radiation Lobectomy for Unresectable Early-Stage Intrahepatic Cholangiocarcinoma

PURPOSE

To validate the safety and effectiveness of radiation segmentectomy (RS) and modified radiation lobectomy (mRL) in intrahepatic cholangiocarcinoma (iCCA) and to evaluate long-term outcomes in patients with unresectable, early-stage iCCA.

MATERIALS AND METHODS

A single-institution, retrospective study of patients with unresectable, solitary iCCA without extrahepatic disease or vascular involvement (Stage I) treated with RS and mRL was performed. Fifteen patients met inclusion criteria (median age, 65.5 years), including 11 (73%) with T1a disease and 4 (27%) with T1b disease. Outcomes included biochemical and clinical toxicities, tumor response by Response Evaluation Criteria in Solid Tumors (RECIST), time to progression, and overall survival (OS).

RESULTS

Median treatment dose was 308.2 Gy (range, 194.2-879.3 Gy). There were no cases of periprocedural mortality or hepatic deterioration. Grade 3+ clinical toxicities occurred in 1 patient (7%). The 3-month and best objective response rates by RECIST were 47% and 60%, respectively. Three patients went on to surgery with explant pathology revealing complete pathologic necrosis. Target lesion progression occurred in 4 patients at a median of 43.4 months. Median OS was 72 months. The 1-, 3-, and 5-year OS rates were 100%, 73.3%, and 50.3%, respectively.

CONCLUSIONS

RS and mRL were safe and effective in treating unresectable, early-stage iCCA. Overall progression of 47% and 5-year OS of 50% were comparable with those of surgical resection. RS and mRL may represent viable therapeutic options for patients with early-stage disease deemed surgically unresectable.

Clinical and dosimetric considerations for yttrium-90 glass microspheres radioembolization of intrahepatic cholangiocarcinoma, metastatic colorectal carcinoma, and metastatic neuroendocrine carcinoma: recommendations from an international multidisciplinary working group

PURPOSE

The TheraSphere Global Steering Committee reconvened to review clinical data and address knowledge gaps related to treatment and dosimetry in non-HCC indications using Yttrium-90 (90Y) glass microspheres.

METHODS

A PubMed search was performed. References were reviewed and adjudicated by the Delphi method. Recommendations were graded according to the degree of recommendation and strength of consensus. Dosimetry focused on a mean dose approach, i.e., aiming for an average dose over either single or multicompartment volumes of interests. Committee discussion and consensus focused on optimal patient selection, disease presentation, liver function, tumour type, tumour vascularity, and curative/palliative treatment intent for intrahepatic cholangiocarcinoma (iCCA) and colorectal and neuroendocrine carcinoma liver metastases (mCRC, mNET).

RESULTS

For all indications, single compartment average perfused volume absorbed dose ≥ 400 Gy is recommended for radiation segmentectomy and 150 Gy for radiation lobectomy. Single compartment 120 Gy for uni- and bilobar treatment reflects current clinical practice, which results in variable tumour and normal tissue absorbed doses. Therefore, multicompartment dosimetry is recommended for uni- and bilobar treatment, aiming for maximum 75 Gy to normal tissue and 150-200 Gy (mCRC, mNET), ≥ 205 (iCCA) tumour absorbed doses. These dose thresholds are preliminary and should be used with caution accounting for patient specific characteristics.

CONCLUSION

Consensus recommendations are provided to guide clinical and dosimetry approaches for 90Y glass microsphere radioembolization in iCCA, mCRC and mNET.

CLINICAL TRIAL NUMBER

not applicable.

Combination therapy strategy based on selective internal radiation therapy as conversion therapy for inoperable giant hepatocellular carcinoma: A case report

BACKGROUND

Hepatocellular carcinoma (HCC) has become a growing health concern globally. Microvascular invasion and high tumor burden are key factors limiting the curative effect of selective internal radiation therapy (SIRT).

CASE SUMMARY

This case study reports a 49-year-old woman who was diagnosed with China Liver Cancer Staging (CNLC) IIIa HCC and > 15 cm tumor diameter. Initially, due to insufficient future liver remnant and vascular invasion, the tumor was unresectable; however, radical hepatectomy was performed after successful conversion therapy with SIRT using yttrium-90 (90Y) resin microspheres followed by hepatic arterial infusion chemotherapy (HAIC) with tyrosine kinase inhibitor (TKI) and anti-programmed death-1 (PD-1) antibody. SIRT using 90Y resin microspheres was given by the right hepatic artery and chemoembolization was simultaneously performed in the tumor's feeding vessels from the right diaphragmatic artery. HAIC was followed every three weeks with lenvatinib and tislelizumab. At 4 months post-SIRT, the tumor was downstaged to CNLC Ib and the patient successfully underwent hepatectomy. The histopathological examination of the resected specimen showed extensive necrosis.

CONCLUSION

This case study provides evidence for an integrated treatment strategy combining SIRT and HAIC with TKI and anti-PD-1 antibodies for patients with large HCC and microvascular invasion. Further confirmatory trials are required in the future.

90Y-Transarterial Radioembolization Combined with Immune Checkpoint Inhibitors in Hepatocellular Carcinoma: A Systematic Review

BACKGROUND

Transarterial radioembolization with yttrium-90 (90Yt-TARE) and immune checkpoint inhibitors (ICIs) are emerging as treatment modalities for intermediate to advanced hepatocellular carcinoma (HCC) based on randomized controlled trials. Herein, we systematically reviewed the published literature on the effects of 90Yt-TARE and ICIs combined on clinical outcomes of HCC.

METHODS

Medical databases of PubMed, Embase, and Cochrane Library were systematically searched for all studies assessing the use of concomitant immunotherapy of ICI with TARE in patients with HCC. Patient characteristics, treatment protocols, treatment outcomes, treatment adverse events, and survival outcomes were extracted after the screening phase. The primary outcomes were overall survival (OS) and patient-free survival (PFS), while the secondary outcomes were imaging objective response (OR) and adverse events.

RESULTS

Among 3432 reviewed, ten studies were included in this systematic review, including four randomized controlled trials and six retrospective studies. These consisted of 413 patients with HCC, and seven studies included patients with Child-Pugh A or B7 scores. Most studies allowed advanced or intermediate HCC stages, but only two specified BCLC stages (B and C). Median tumor sizes ranged from 56 to 78.5 mm. Various agents with different administration schedules were used as ICIs for immunotherapy by different studies for the combination of 90Yt-TARE with ICIs. Median OS ranged from 16.2 to 27 months between different studies while the PFS also ranged from 5.6 to 13.3 months. The OR rates according to imaging-based response assessments were reported between 31 and 89%, and the incidence rate of any grade toxicities was between 50 and 80%.

CONCLUSION

Concomitant treatment with 90Yt-TARE and ICIs has shown promising results in the treatment of patients with HCC. Further studies are required to reach a consensus on the optimal treatment protocol and the outcome of these treatments for patients with intermediate to advanced HCC.

Voxel-Based Dosimetry Predicts Local Tumor Progression Post 90 Y Radiation Segmentectomy of Colorectal Liver Metastases

BACKGROUND

Radiation segmentectomy (RS) is an alternative potential local curative treatment for selected colorectal liver metastases (CLMs) not amenable to ablation or limited resection.

PURPOSE

The aim of this study was to evaluate the dosimetric response of low volume CLMs to RS in heavily pretreated patients who are not candidates for resection or percutaneous ablation.

PATIENTS AND METHODS

This single-center retrospective study evaluated CLMs patients treated with RS (prescribed tumor dose >190 Gy) from 2015 to 2023. RS doses to tumor(s) and margins were calculated from SPECT/CT and PET/CT images. Response and local tumor progression (LTP) were assessed using anatomic (RECIST 1.1) and metabolic (PERCIST) criteria. LTP-free survival (LTPFS) and overall survival were estimated with Kaplan-Meier methodology. Variables were assessed as predictors of LTPFS using the Cox proportional hazards model.

RESULTS

Thirty-six patients underwent 38 RS procedures to treat 57 tumors. Median time from initial diagnosis to detection of liver metastases and RS were 16.4 (interquartile range: 6.5-32.2) and 26.8 (interquartile range: 12.5-40.0) months, respectively. Median overall survival after RS was 14.3 (95% confidence interval [CI]: 10.8-30.7) months. Predictors of LTPFS included tumor number(s), mean tumor dose (MTD), and margin mean absorbed dose (MMAD). Complete radiographic (hazards ratio [HR]: 1.29e-16, 95% CI: 4.06e-17-4.07e-16, P < 0.001) and metabolic response (HR: 0.38, 95% CI: 0.15-0.95, P = 0.038) correlated with prolonged LTPFS. One-year LTPFS rate was 83.3% for tumors receiving MTD ≥400 Gy and a 5-mm surrounding MMAD ≥350 Gy ( P = 0.006). No instances of LTP were observed when tumors received stereotactic irradiation over 300 Gy (at least 95% of the tumor volume received ≥300 Gy). One-year LTPFS rate for tumors receiving MTD ≥400 Gy was 68.6% versus 14.3% for those that did not reach this threshold ( P = 0.013). In multivariate analysis, MTD ≥400 Gy and 5-mm MMAD ≥350 Gy were independent predictors of LTPFS (HR: 0.11; 95% CI: 0.01-0.81; P = 0.03).

CONCLUSIONS

MTD ≥400 Gy, MMAD ≥350 Gy, and stereotactic tumor irradiation ≥300 Gy are associated with prolonged LTPFS after RS for CLMs.

EASL Clinical Practice Guidelines on the management of hepatocellular carcinoma

Liver cancer is the third leading cause of cancer-related deaths worldwide, with hepatocellular carcinoma (HCC) accounting for approximately 90% of primary liver cancers. Advances in diagnostic and therapeutic tools, along with improved understanding of their application, are transforming patient treatment. Integrating these innovations into clinical practice presents challenges and necessitates guidance. These clinical practice guidelines offer updated advice for managing patients with HCC and provide a comprehensive review of pertinent data. Key updates from the 2018 EASL guidelines include personalised surveillance based on individual risk assessment and the use of new tools, standardisation of liver imaging procedures and diagnostic criteria, use of minimally invasive surgery in complex cases together with updates on the integrated role of liver transplantation, transitions between surgical, locoregional, and systemic therapies, the role of radiation therapies, and the use of combination immunotherapies at various stages of disease. Above all, there is an absolute need for a multiparametric assessment of individual risks and benefits, considering the patient's perspective, by a multidisciplinary team encompassing various specialties.

Yttrium-90 Radiation Segmentectomy for Treatment of Neuroendocrine Liver Metastases

PURPOSE

To assess the safety and effectiveness of yttrium-90 (90Y) radiation segmentectomy (RS) for neuroendocrine tumor liver metastases (NELMs).

MATERIALS AND METHODS

This single-institution retrospective study included 18 patients with 23 liver tumors not amenable to resection or ablation, who underwent RS between 2009 and 2021. Tumor grades by Ki-67/mitotic indices were Grade I (n = 9/23, 39%), Grade II (n = 10/23, 45%), and Grade III (n = 4/23, 17%). Eleven patients (61%) were previously treated with somatostatin analogs, 5 (28%) with chemotherapy, and 2 (11%) with peptide receptor radionuclide therapy. Safety was assessed with preprocedural/postprocedural liver chemistries, blood counts, and clinical adverse events (AEs) using National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. Tumor response was assessed per Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1 and modified RECIST (mRECIST) criteria. Kaplan-Meier analysis was used to estimate median overall survival (OS), progression-free survival (PFS), and time to progression (TTP) from the date of 90Y.

RESULTS

Median follow-up was 31.9 months. Grade 1 fatigue was observed in 13 of 18 patients (72%), with 1 of 18 patients (6%) experiencing Grade 3 fatigue. Three patients (17%) exhibited Grade 3 lymphopenia. No other Grade 3 or any Grade 4 AE was observed. Tumor objective response was achieved in 83% of patients by RECIST size criteria and 100% by mRECIST enhancement criteria. Median OS was 69.4 months (95% CI, 23.1-99.4), and median PFS was 12.2 months (95% CI, 4.6-28.8). Median overall TTP was 13.0 months (95% CI, 4.6-45.1), with median treated tumor TTP not reached.

CONCLUSIONS

90Y RS demonstrated high rates of antitumor response with a favorable toxicity profile and durable OS in the treatment of NELMs.

Radiation segmentectomy for early hepatocellular carcinoma is curative

In this expert opinion, we provide the rationale for concluding that radiation segmentectomy (using the RADSEG method) - a technique involving the transarterial delivery of an ablative, complete necrosis-inducing dose of yttrium-90 radiotherapy - is curative in limited-disease burden hepatocellular carcinoma (HCC). Currently, curative options for early stage and other carefully selected HCC cases include transplantation, resection, and ablation. Because of issues with organ availability, co-morbidities preventing resection, and tumour size and location limiting ablation, other treatments are necessary for this selected patient population. The RADSEG method has evolved into an intra-arterial approach in this setting, with long-term outcomes comparable to ablation, resection, and transplantation. It is proposed that yttrium-90 radioembolisation, applying the RADSEG technique, be formally recognised as curative for early HCC.

Streamlining Radioembolization without Lung Shunt Estimation versus Regular Radioembolization in Patients with Hepatocellular Carcinoma within the Milan Criteria

PURPOSE

To assess the effectiveness and safety of streamlining transarterial radioembolization (S-TARE) without lung shunt fraction estimation using nuclear medicine imaging, compared with regular transarterial radioembolization (R-TARE), for patients with hepatocellular carcinoma (HCC) within the Milan criteria.

MATERIALS AND METHODS

Between January 2012 and December 2022, 100 consecutive patients with HCC within the Milan criteria underwent R-TARE (n = 38) or S-TARE (n = 62) and were retrospectively analyzed. Adverse events, complete response (CR) rates, and time to progression (TTP) by the modified Response Evaluation Criteria in Solid Tumours (mRECIST) and localized mRECIST following each treatment were compared using the Fisher exact test and Kaplan-Meier curve analyses with covariate adjustment.

RESULTS

Serious adverse events ≥ Grade 3 occurred in 3 (7.9%, 3/38) and 2 (3.2%, 2/62) patients following R-TARE and S-TARE, respectively (P = .365). No patients developed radiation pneumonitis. Among the 84 patients treated with glass microspheres, the CR rates were not significantly different after R-TARE (96.9%, 31/32) and S-TARE (90.4%, 47/52) (P = .400). There was no significant difference in TTP by mRECIST between R-TARE and S-TARE (unadjusted P = .400, adjusted P = .712). For patients with a single HCC, no significant difference was observed in TTP by localized mRECIST (unadjusted P = .090, adjusted P = .242). In the 16 patients treated with resin microspheres, the CR rates were 66.7% (4/6) for R-TARE and 90% (9/10) for S-TARE, respectively (P = .518).

CONCLUSIONS

S-TARE using yttrium-90 glass or resin microspheres was as effective and safe as R-TARE for HCC within the Milan criteria.

Using Voxel-Based Dosimetry to Evaluate Sphere Concentration and Tumor Dose in Hepatocellular Carcinoma Treated with Yttrium-90 Radiation Segmentectomy with Glass Microspheres

PURPOSE

To utilize voxel-based dosimetry following radiation segmentectomy (RS) to understand microsphere distribution and validate current literature regarding radiologic and pathologic outcomes.

MATERIALS AND METHODS

A retrospective, single-center analysis of patients with solitary hepatocellular carcinoma (N = 56) treated with yttrium-90 (90Y) RS with glass microspheres (Therasphere; Boston Scientific, Marlborough, Massachusetts) from 2020 to 2022 was performed. Posttreatment voxel-based dosimetry was evaluated using Mirada DBx Build 1.2.0 Simplicit90Y software (Boston Scientific) and utilized to calculate sphere concentration to tumor as well as D70 (minimum dose to 70% total tumor volume), D90, and D99. Time to progression (TTP), treatment response, and adverse events were studied.

RESULTS

Fifty-six solitary tumors were analyzed with a median tumor diameter of 3.4 cm (range, 1.2-6.8 cm) and median tumor absorbed dose of 732 Gy (range, 252-1,776 Gy). Median sphere activity (SA) at the time of delivery was 1,446 Bq (range, 417-2,621 Bq). Median tumor sphere concentration was 12,868 spheres/mL (range, 2,655-37,183 spheres/mL). Sphere concentration into tumor and normal tissue was inversely correlated with perfused treatment volume (R2 = 0.21 and R2 = 0.39, respectively). Of the 51 tumors with posttreatment imaging, objective response was noted in 49 patients (96%) and complete response in 42 patients (82%). The median TTP was not reached with a 2-year progression rate of 11%. Fifteen patients underwent liver transplant. Median tumor necrosis was 99% (range, 80%-100%). Lower tumor volumes and higher D99 were associated with complete pathologic necrosis (P < .001 and P = .022, respectively).

CONCLUSIONS

Voxel-based dosimetry following 90Y radioembolization can be utilized to account for sphere deposition and distribution into tumor. Ablative RS with high SA yields durable radiologic and pathologic outcomes.

Yttrium-90 radioembolization treatment strategies for management of hepatocellular carcinoma

As the third leading cause of cancer-related deaths worldwide, hepatocellular carcinoma (HCC) represents a significant global health challenge. This paper provides an introduction and comprehensive review of transarterial radioembolization (TARE) with Yttrium-90 (Y90), a widely performed transcatheter procedure for HCC patients who are not suitable candidates for surgery. TARE involves the targeted delivery of radioactive microspheres to liver tumors, offering a promising treatment option for managing HCC across various stages of the disease. By evaluating Y90 TARE outcomes across early, intermediate, and advanced stages of HCC, the review aims to present a thorough understanding of its efficacy and safety. Additionally, this paper highlights future research directions focusing on the potential of combination therapies with systemic and immunotherapies, as well as personalized treatments. The exploration of these innovative approaches aims to improve treatment outcomes, reduce adverse events, and provide new therapeutic opportunities for HCC patients. The review underscores the importance of ongoing research and clinical trials to optimize TARE further and integrate it into comprehensive HCC treatment paradigms.

Voxel-based tumor dose correlates to complete pathologic necrosis after transarterial radioembolization for hepatocellular carcinoma

PURPOSE

The transarterial radioembolization (TARE) dose is traditionally calculated using the single-compartment Medical Internal Radiation Dose (MIRD) formula. This study utilized voxel-based dosimetry to correlate tumor dose with explant pathology in order to identify dose thresholds that predicted response.

METHODS

All patients with HCC treated with TARE using yttrium-90 [90Y] glass microspheres at a single institution between January 2015 - June 2023 who underwent liver transplantation were eligible. The [90Y] distribution and dose-volume histograms were determined using Simplicity90 (Mirada Medical, Oxford UK) with a Bremsstrahlung SPECT/CT. A complete response was assigned if explant pathology showed complete necrosis and the patient had not undergone additional treatments to the same tumor after TARE. Logistic regression and receiver operator characteristic (ROC) curves were constructed to evaluate dose thresholds correlated with response.

RESULTS

Forty-one patients were included. Twenty-six (63%) met criteria for complete response. Dose to 95% (D95), 70% (D70), and 50% (D50) of the tumor volume were associated with likelihood of complete response by logistic regression (all p < 0.05). For lesions with complete response versus without, the median D95 was 813 versus 232 Gy, D70 was 1052 versus 315 Gy, and D50 was 1181 versus 369 Gy (all p < 0.01). A D95 > 719 Gy had the highest accuracy at 68% (58% sensitivity, 87% specificity) for predicting complete response. Median percent of tumor volume receiving at least 100 Gy (V100), 200 Gy (V200), 300 Gy (V300), and 400 Gy (V400) also differed by pathologic response: the median V100, V200, V300, and V400 was 100% versus 99%, 100% versus 97%, 100% versus 74%, and 100% versus 43% in the complete response versus non-complete response groups, respectively (all p < 0.05).

CONCLUSION

Voxel-based dosimetry was well-correlated with explant pathology. The D95 threshold had the highest accuracy, suggesting the D95 may be a relevant target for multi-compartment dosimetry.

Locoregional Therapies for Hepatocellular Carcinoma in Patients with Nonalcoholic Fatty Liver Disease

Hepatocellular carcinoma (HCC) is the third most common cause of cancer-related death worldwide with an average five-year survival rate in the US of 19.6%. With the advent of HBV and HCV treatment and prevention, along with the rising rates of obesity, nonalcoholic fatty liver disease (NAFLD) and metabolic syndrome are set to overtake infectious causes as the most common cause of HCC. While surgical resection and transplantation can be curative when amenable, the disease is most commonly unresectable on presentation, and other treatment approaches are the mainstay of therapy. In these patients, locoregional therapies have evolved as a vital tool in both palliation for advanced disease and as a bridge to surgical resection and transplantation. In this review, we will be exploring the primary locoregional therapies for HCC in patients with NAFLD, including transarterial chemoembolization (TACE), bland transarterial embolization (TAE), transarterial radioembolization (TARE), and percutaneous ablation.

Assessment of real-time US-CT/MR-guided percutaneous gold fiducial marker implementation in malignant hepatic tumors for stereotactic body radiation therapy

BACKGROUNDS/AIMS

This study explored the initial institutional experience of using gold fiducial markers for stereotactic body radiotherapy (SBRT) in treating malignant hepatic tumors using real-time ultrasound-computed tomography (CT)/magnetic resonance (MR) imaging fusion-guided percutaneous placement.

METHODS

From May 2021 to August 2023, 19 patients with 25 liver tumors that were invisible on pre-contrast CT received fiducial markers following these guidelines. Postprocedural scans were used to confirm their placement. We assessed technical and clinical success rates and monitored complications. The implantation of fiducial markers facilitating adequate treatment prior to SBRT, which was achieved in 96% of the cases (24 of 25 tumors), was considered technical success. Clinical success was the successful completion of SBRT without evidence of marker displacement and was achieved in 88% of cases (22 of 25 tumors). Complications included one major subcapsular hematoma and marker migration into the right atrium in two cases, which prevented SBRT.

RESULTS

Among the treated tumors, 20 of 24 (83.3%) showed a complete response, three of 24 (12.5%) remained stable, and one of 24 (4.2%) progressed during an average 11.7-month follow-up (range, 2-32 months).

CONCLUSIONS

This study confirms that percutaneous gold fiducial marker placement using real-time CT/MR guidance is effective and safe for SBRT in hepatic tumors, but warns of marker migration risks, especially near the hepatic veins and in subcapsular locations. Using fewer markers than traditionally recommended-typically two per patient, the outcomes were still satisfactory, particularly given the increased risk of migration when markers were placed near major hepatic veins.

Examining the Efficacy and Safety of Combined Locoregional Therapy and Immunotherapy in Treating Hepatocellular Carcinoma

More than 800,000 people worldwide are diagnosed with HCC (hepatocellular carcinoma) each year, with approximately 700,000 deaths alone occurring in that same year. Treatment of HCC presents complex therapeutic challenges, particularly in intermediate and advanced stages. LRTs such as transarterial chemoembolization (TACE) and ablations have been the mainstay treatment for early to intermediate-stage HCC, and systemic therapies are used to treat intermediate-late-stage HCC. However, novel literature describing combining LRT with systemic therapies has shown promising results. This review explores recent advances in both liver-directed techniques for hepatocellular carcinoma, including bland transarterial embolization, chemoembolization, radioembolization, and ablative therapies in conjunction as well as with systemic therapies, with a focus on combination therapies, patient selection, procedural technique, periprocedural management, and outcomes. Our findings suggest that LRT combined with systemic therapies is a viable strategy for improving progression-free survival and time to progression for patients with intermediate-to-late-stage HCC. However, further investigation is required to refine treatment protocols and define patient cohorts that would benefit the most.

Influence of Early Versus Delayed Hepatic Artery Perfusion Scan on 90Y Selective Internal Radiation Therapy Planning

Purpose: This study evaluated the effect of an increase in the time interval between hepatic intra-arterial injection of 99mTc-macroaggregated albumin (MAA) and hepatic artery perfusion scintigraphy (HAPS) on the lung shunt fraction (LSF) and perfused volume (PV) calculations in the treatment planning of selective internal radiation therapy (SIRT). Methods: The authors enrolled 51 HAPS sessions from 40 patients diagnosed with primary or metastatic liver malignancy. All patients underwent scan at the first and fourth hour after hepatic arterial injection of 99mTc-MAA. Based on single-photon emission computed tomography images, LSF values were measured from each patient's first and fourth hour images. PV1 and PV4 were also calculated based on three-dimensional images using 5% and 10% cutoff threshold values and compared with each other. Results: The authors found that the median of LSF4 was statistically significantly higher than LSF1 (3.05 vs. 4.14, p ≤ 0.01). There was no statistically significant difference between PV1 and PV4 on the 10% (p = 0.72) thresholds. Conclusions: LSF values can be overestimated in case of delayed HAPS, potentially leading to treatment cancellation due to incorrectly high results in patients who could benefit from SIRT. Threshold-based PV values do not significantly change over time; nevertheless, keeping the short interval time would be safer.

Interventional radiology meets immuno-oncology for hepatocellular carcinoma

Locoregional and systemic therapies are the most used treatment options for patients with hepatocellular carcinoma (HCC). Interventional radiologists have improved and developed novel protocols and devices for both intratumoural ablative approaches with curative intent and various transarterial intrahepatic treatment options, which have continuously improved patient outcomes. Two large phase III randomised clinical trials have demonstrated the efficacy of different immune checkpoint inhibitors either as single agents or in combination in the first-line setting and immunotherapy has become the standard first-line treatment option for patients with advanced HCC. Herein, we discuss advances and perspectives in the area of interventional radiology (IR) and immune-oncology (IO). We summarise results from recent studies and provide an overview of ongoing studies in IR and IO. Based on the significant advances in both areas, we propose that IR and IO need to cover the emerging "discipline" of IR-IO, in which we develop and test novel approaches to combine locoregional therapies with immunotherapy, in order to develop sufficient evidence for them to be considered standard of care for patients with HCC in the near future.

Selective internal radiation therapy segmentectomy: A new minimally invasive curative option for primary liver malignancies?

Transarterial radioembolization or selective internal radiation therapy (SIRT) has emerged as a minimally invasive approach for the treatment of tumors. This percutaneous technique involves the local, intra-arterial delivery of radioactive microspheres directly into the tumor. Historically employed as a palliative measure for liver malignancies, SIRT has gained traction over the past decade as a potential curative option, mirroring the increasing role of radiation segmentectomy. The latest update of the BCLC hepatocellular carcinoma guidelines recognizes SIRT as an effective treatment modality comparable to other local ablative methods, particularly well-suited for patients where surgical resection or ablation is not feasible. Radiation segmentectomy is a more selective approach, aiming to deliver high-dose radiation to one to three specific hepatic segments, while minimizing damage to surrounding healthy tissue. Future research efforts in radiation segmentectomy should prioritize optimizing radiation dosimetry and refining the technique for super-selective administration of radiospheres within the designated hepatic segments.

Long-term Clinical Outcomes of Yttrium-90 Transarterial Radioembolization for Hepatocellular Carcinoma: A 5-Year Institutional Experience

RATIONALE AND OBJECTIVES

To examine the clinical outcomes of yttrium-90 (Y90) transarterial radioembolization (TARE) for primary hepatocellular carcinoma (HCC) through the evaluation of a 5-year institutional experience.

MATERIALS AND METHODS

This retrospective study evaluated 88 consecutive patients with primary HCC receiving Y90 TARE treatment at an academic medical center from 2017 to 2021. Disease distribution was bilobar in 60.2% of patients with an average lesion diameter of 5.0 ± 3.4 cm and Barcelona Clinic Liver Cancer stage B or C in 77% of the participants. Clinical outcomes were elucidated by examination of complications, liver function tests, biochemical response, and radiographic response. Objective response ratio (ORR) and progression-free survival (PFS) were also calculated.

RESULTS

The mean administered Y90 radiation dose was 127.8 ± 20.2 Gy. No significant complications or LFT elevations occurred post-therapy. Of the 73.9% of patients with α-fetoprotein-producing tumors, 67.8% experienced a complete or partial biochemical response 1 month post-treatment. The ORR was 83.3% on 6-month imaging and PFS was 9.6 ± 8.5 months. Functional outcomes (Eastern Cooperative Oncology Group) were maintained or improved in 79.6% and 76.1% of patients by 6 months and 1 year post-treatment, respectively. The mean survival was 14.7 ± 12.1 months. At 6 months post-treatment, 77.3% of patients were downstaged to or maintained Milan criteria, which was sustained for 74.4% and 70.0% of patients 1 year and 2 years after treatment, respectively.

CONCLUSION

Y90-TARE is a safe and effective therapy for primary HCC. Enduring outcomes further act as a realistic bridge to liver transplantation, with a majority of patients maintaining Milan criteria and preserving their functional status long term.

Efficacy and Safety of Radiation Segmentectomy with 90Y Resin Microspheres for Hepatocellular Carcinoma

Background Limited data are available on radiation segmentectomy (RS) for treatment of hepatocellular carcinoma (HCC) using yttrium 90 (90Y) resin microsphere doses determined by using a single-compartment medical internal radiation dosimetry (MIRD) model. Purpose To evaluate the efficacy and safety of RS treatment of HCC with 90Y resin microspheres using a single-compartment MIRD model and correlate posttreatment dose with outcomes. Materials and Methods This retrospective single-center study included adult patients with HCC who underwent RS with 90Y resin microspheres between July 2014 and December 2022. Posttreatment PET/CT and dosimetry were performed. Adverse events were assessed using the Common Terminology Criteria for Adverse Events, version 5.0. Per-lesion and overall response rates (ie, complete response [CR], objective response, disease control, and duration of response) were assessed at imaging using the Modified Response Evaluation Criteria in Solid Tumors, and overall survival (OS) was assessed using Kaplan-Meier analysis. Results Among 67 patients (median age, 69 years [IQR, 63-78 years]; 54 male patients) with HCC, median tumor absorbed dose was 232 Gy (IQR, 163-405 Gy). At 3 months, per-lesion and overall (per-patient) CR was achieved in 47 (70%) and 41 (61%) of 67 patients, respectively. At 6 months (n = 46), per-lesion rates of objective response and disease control were both 94%, and per-patient rates were both 78%. A total of 88% (95% CI: 79 99) and 72% (95% CI: 58, 90) of patients had a per-lesion and overall duration of response of 1 year or greater. At 1 month, a grade 3 clinical adverse event (abdominal pain) occurred in one of 67 (1.5%) patients. Median posttreatment OS was 26 months (95% CI: 20, not reached). Disease progression at 2 years was lower in the group that received 300 Gy or more than in the group that received less than 300 Gy (17% vs 61%; P = .047), with no local progression in the former group through the end of follow-up. Conclusion Among patients with HCC who underwent RS with 90Y resin microspheres, 88% and 72% achieved a per-lesion and overall duration of response of 1 year or greater, respectively, with one grade 3 adverse event. In patients whose tumors received 300 Gy or more according to posttreatment dosimetry, a disease progression benefit was noted. © RSNA, 2024 Supplemental material is available for this article.

Locoregional Therapies for Hepatocellular Carcinoma prior to Liver Transplant: Comparative Pathologic Necrosis, Radiologic Response, and Recurrence

PURPOSE

To compare pathologic tumor necrosis rates after locoregional therapies (LRTs) for hepatocellular carcinoma (HCC) prior to liver transplantation and evaluate radiologic-pathologic correlation along with posttransplant HCC recurrence.

MATERIALS AND METHODS

Consecutive patients with solitary HCC bridged or downstaged with LRT from 2010 to 2022 were included. LRTs were transarterial chemoembolization (TACE), radioembolization (yttrium-90 [90Y]), ablation, and stereotactic body radiotherapy (SBRT). Upfront combination therapy options were TACE/ablation and TACE/SBRT. Subsequent therapy crossover due to local recurrence was allowed. Posttreatment imaging closest to the time of transplant, explant histopathologic necrosis, and tumor recurrence after transplant were reviewed.

RESULTS

Seventy-three patients met inclusion criteria, of whom 5 (7%) required downstaging. 90Y alone (n = 36) and multimodal therapy (pooled upfront combination and crossover therapy, n = 23) resulted in significantly greater pathologic necrosis compared with TACE alone (n = 14; P = .01). High dose 90Y radiation segmentectomy (≥190 Gy; n = 27) and TACE/ablation (n = 7) showed highest rates of complete pathologic necrosis (CPN)-63% (n = 17) and 71% (n = 5), respectively. Patients with CPN had a mean lesion size of 2.5 cm, compared with 3.2 cm without CPN (P = .04), irrespective of LRT modality. HCC recurrence was more common in patients without CPN (16%, 6/37) than in those with CPN (3%, 1/36; P = .11). Using Liver Imaging Reporting and Data System (LI-RADS), a nonviable imaging response was 75% sensitive and 57% specific for CPN.

CONCLUSIONS

Radiation segmentectomy and multimodal therapy significantly improved CPN rates compared with TACE alone. A LI-RADS treatment response of nonviable did not confidently predict CPN.

Radiation Segmentectomy for the Treatment of Hepatocellular Carcinoma: A Practical Review of Evidence

Radiation segmentectomy is a versatile, safe, and effective ablative therapy for early-stage hepatocellular carcinoma. Advances in radiation segmentectomy patient selection, procedural technique, and dosimetry have positioned this modality as a curative-intent and guideline-supported treatment for patients with solitary HCC. This review describes key radiation segmentectomy concepts and summarizes the existing literary knowledgebase.

Long-Term Overall Survival After Selective Internal Radiation Therapy for Locally Advanced Hepatocellular Carcinomas: Updated Analysis of DOSISPHERE-01 Trial

Interim analysis of the DOSISPHERE-01 study demonstrated a strong improvement in response and overall survival (OS) on using 90Y-loaded glass microspheres with personalized dosimetry compared with standard dosimetry in patients with nonoperable locally advanced hepatocellular carcinoma. This report sought to provide a long-term analysis of OS. Methods: In this phase II study (ClinicalTrials.gov identifier NCT02582034), treatment was randomly assigned (1:1) with the goal to deliver either at least 205 Gy (if possible >250-300 Gy) to the index lesion in the personalized dosimetry approach (PDA) or 120 ± 20 Gy to the treated volume in the standard dosimetry approach (SDA). The 3-mo response of the index lesion was the primary endpoint, with OS being one of the secondary endpoints. This report is a post hoc long-term analysis of OS. Results: Overall, 60 hepatocellular carcinoma patients with at least 1 lesion larger than 7 cm and more than 30% of hepatic reserve were randomized (intent-to-treat population: PDA, n = 31; SDA, n = 29), with 56 actually treated (modified intent-to-treat population: n = 28 in each arm). The median follow-up for long-term analysis was 65.8 mo (range, 2.1-73.1 mo). Median OS was 24.8 mo and 10.7 mo (hazard ratio [HR], 0.51; 95% CI, 0.29-0.9; P = 0.02) for PDA and SDA, respectively, in the modified intent-to-treat population. Median OS was 22.9 mo for patients with a tumor dose of at least 205 Gy, versus 10.3 mo for those with a tumor dose of less than 205 Gy (HR, 0.42; 95% CI, 0.22-0.81; P = 0.0095), and was 22.9 mo for patients with a perfused liver dose of 150 Gy or higher, versus 10.3 mo for those with a perfused liver dose of less than 150 Gy (HR, 0.42; 95% CI, 0.23-0.75; P = 0.0033). Lastly, median OS was not reached in patients who were secondarily resected (n = 11, 10 in the PDA group and 1 in the SDA group), versus 10.8 mo in those without secondary resection (n = 45) (HR, 0.17; 95% CI, 0.065-0.43; P = 0.0002). Only resected patients displayed favorable long-term OS rates, meaning an OS of more than 50% at 5 y. Conclusion: After longer follow-up, personalized dosimetry sustained a meaningful improvement in OS, which was dramatically improved for patients who were accurately downstaged toward resection, including most portal vein thrombosis patients.

Radiation Segmentectomy for Hepatocellular Carcinoma

The application of trans-arterial radioembolization (TARE) with Yttrium-90, historically a palliative treatment option for patients with advanced hepatocellular carcinoma (HCC), is evolving. Radiation segmentectomy (RADSEG), the segmental delivery of an ablative radiation dose, is a treatment option for patients with earlier-stage HCC. This review presents an in-depth exploration of RADSEG, emphasizing its technical considerations, dosimetry advancements, and patient selection. The integration of RADSEG into the Barcelona Clinic Liver Cancer (BCLC) paradigm will be highlighted. RADSEG outcomes concerning safety and efficacy will be explored and compared with traditional locoregional cancer treatments like trans-arterial chemoembolization (TACE), percutaneous thermal ablation, and surgical resection, with an eye on future directions and considerations.

Management of Intermediate-Stage Hepatocellular Carcinoma: Systemic Versus Locoregional Therapy

Intermediate-stage hepatocellular carcinoma (HCC) comprises a heterogeneous group of patients with varying levels of tumor burden. Transarterial chemoembolization was traditionally the mainstay of treatment for intermediate-stage HCC for almost 2 decades. New and emerging treatment options have revolutionized HCC therapy, allowing for broader application to patients with intermediate- and advanced-stage disease. Accordingly, new guidelines acknowledge these options, and intermediate stage HCC can now be treated with surgical, locoregional or systemic therapies, or a combination thereof. Patients will continue to benefit from the development of complex treatment strategies in a multidisciplinary setting to optimize individual outcomes.

Hepatocellular Carcinoma: Surgical Management and Evolving Therapies

Hepatocellular carcinoma (HCC) is the fifth most common cancer in men and the eighth most common cancer in women worldwide. It is also the second leading cause of cancer death worldwide, with 780,000 deaths in 2018. Seventy-two percent of HCC cases occur in Asia, 10% in Europe, 8% in Africa, 5% in North America, and 5% in Latin America (Singal et al. in J Hepatol 72(2):250-261, 2020 [1]).

Early post-treatment MRI predicts long-term hepatocellular carcinoma response to radiation segmentectomy

OBJECTIVES

Radiation segmentectomy using yttrium-90 plays an emerging role in the management of early-stage HCC. However, the value of early post-treatment MRI for response assessment is uncertain. We assessed the value of response criteria obtained early after radiation segmentectomy in predicting long-term response in patients with HCC.

MATERIALS AND METHODS

Patients with HCC who underwent contrast-enhanced MRI before, early, and 12 months after radiation segmentectomy were included in this retrospective single-center study. Three independent radiologists reviewed images at baseline and 1st follow-up after radiation segmentectomy and assessed lesion-based response according to mRECIST, LI-RADS treatment response algorithm (TRA), and image subtraction. The endpoint was response at 12 months based on consensus readout of two separate radiologists. Diagnostic accuracy for predicting complete response (CR) at 12 months based on the 1st post-treatment MRI was calculated.

RESULTS

Eighty patients (M/F 60/20, mean age 67.7 years) with 80 HCCs were assessed (median size baseline, 1.8 cm [IQR, 1.4-2.9 cm]). At 12 months, 74 patients were classified as CR (92.5%), 5 as partial response (6.3%), and 1 as progressive disease (1.2%). Diagnostic accuracy for predicting CR was fair to good for all readers with excellent positive predictive value (PPV): mRECIST (range between 3 readers, accuracy: 0.763-0.825, PPV: 0.966-1), LI-RADS TRA (accuracy: 0.700-0.825, PPV: 0.983-1), and subtraction (accuracy: 0.775-0.825, PPV: 0.967-1), with no difference in accuracy between criteria (p range 0.053 to > 0.9).

CONCLUSION

mRECIST, LI-RADS TRA, and subtraction obtained on early post-treatment MRI show similar performance for predicting long-term response in patients with HCC treated with radiation segmentectomy.

CLINICAL RELEVANCE STATEMENT

Response assessment extracted from early post-treatment MRI after radiation segmentectomy predicts complete response in patients with HCC with high PPV (≥ 0.96).

KEY POINTS

• Early post-treatment response assessment on MRI predicts response in patients with HCC treated with radiation segmentectomy with fair to good accuracy and excellent positive predictive value. • There was no difference in diagnostic accuracy between mRECIST, LI-RADS, and subtraction for predicting HCC response to radiation segmentectomy.

Chemoembolization Plus Ablation: Current Status

Hepatocellular carcinoma (HCC) is a leading cause of cancer-related death worldwide. The treatment landscape for HCC has evolved significantly over the past decade, with several modalities available to treat various stages of disease. The Barcelona Clinic Liver Cancer (BCLC) system provides a foundation for treatment guidance. However, given the complex nature of HCC, a more nuanced approach is often required, especially for lesions sized between 3 and 5 cm. This review aims to analyze the available treatments for early-stage HCC lesions between 3 and 5 cm, with a focus on the therapeutic potential and efficacy of transarterial chemoembolization (TACE)-ablation. Additional therapies including TACE, ablation, transarterial radioembolization, and surgical resection are also reviewed and compared with TACE-ablation. TACE-ablation is a viable therapeutic option for early-stage HCC lesions between 3 and 5 cm. Surgical resection remains the gold standard. Although recent studies suggest radiation segmentectomy may be a curative approach for this patient population, further studies are needed to compare the relative efficacies between TACE-ablation and radiation segmentectomy.

Ablation versus Radiation Segmentectomy for Small Liver Tumors

Hepatocellular carcinoma (HCC) is a liver malignancy that affects more than a million people worldwide with a complex multifactorial etiology. After the diagnosis of HCC is made, physicians establish management using the Barcelona Clinic Liver Cancer (BCLC) guidelines revolving around tumor stage, liver function, performance status, and patient preferences. According to recent updates to these guidelines, thermal ablation is the second-best curative option apart from surgical resection for small HCC (< 2 cm). While thermal ablation is standard of care, recent studies have suggested that radiation segmentectomy (RS) has similar outcomes, limited hepatotoxicity, and ultimately a cost-efficient approach. Although there is limited literature on RS, this article compares ablation techniques against radiation segmentectomy for small HCC tumors.

Update on Locoregional Therapies for Liver Cancer: Radiation Segmentectomy

Over 900,000 people worldwide were diagnosed with liver cancer in 2022 alone, with hepatocellular carcinoma (HCC) accounting for 75-85% of cases. Treatment for HCC includes some combination of systemic therapies, surgery, liver transplantation, ablation, and intra-arterial therapies with transarterial chemoembolization (TACE) or transarterial radioembolization (TARE). Currently, the Barcelona Clinic Liver Cancer (BCLC) guidelines have acknowledged liver transplantation, surgical resection, and thermal ablation as curative therapies in very early to early stage HCC (BCLC-0 and BCLC-A). While these modalities are the preferred curative treatments for a very early to early stage disease, there are challenges associated with these options, such as organ availability and patient eligibility. Current data shows the role of radiation segmentectomy as a curative therapeutic option for very early to early stage HCC that is unresectable and not amenable to ablation. As future data continues to elucidate the ability for radiation segmentectomy to achieve complete pathologic necrosis, the goal is for the BCLC staging model to acknowledge its role as a curative treatment in this patient population and incorporate it into the ever-evolving guidelines.

Early Prediction of Response of Hepatocellular Carcinoma to Yttrium-90 Radiation Segmentectomy Using a Machine Learning MR Imaging Radiomic Approach

PURPOSE

To assess the accuracy of a machine learning (ML) approach based on magnetic resonance (MR) imaging radiomic quantification obtained before treatment and early after treatment for prediction of early hepatocellular carcinoma (HCC) response to yttrium-90 transarterial radioembolization (TARE).

MATERIALS AND METHODS

In this retrospective single-center study of 76 patients with HCC, baseline and early (1-2 months) post-TARE MR images were collected. Semiautomated tumor segmentation facilitated extraction of shape, first-order histogram, and custom signal intensity-based radiomic features, which were then trained (n = 46) using a ML XGBoost model and validated on a separate cohort (n = 30) not used in training to predict treatment response assessed at 4-6 months (based on modified Response and Evaluation Criteria in Solid Tumors criteria). Performance of this ML radiomic model was compared with those of models comprising clinical parameters and standard imaging characteristics using area under the receiver operating curve (AUROC) analysis for prediction of complete response (CR).

RESULTS

Seventy-six tumors with a mean (±SD) diameter of 2.6 cm ± 1.6 were included. Sixty, 12, 1, and 3 patients were classified as having CR, partial response, stable disease, and progressive disease, respectively, at 4-6 months posttreatment on the basis of MR images. In the validation cohort, the radiomic model showed good performance (AUROC, 0.89) for prediction of CR, compared with models comprising clinical and standard imaging criteria (AUROC, 0.58 and 0.59, respectively). Baseline imaging features appeared to be more heavily weighted in the radiomic model.

CONCLUSIONS

The use of ML modeling of radiomic data combining baseline and early follow-up MR imaging could predict HCC response to TARE. These models need to be investigated further in an independent cohort.

Contemporary applications of Y90 for the treatment of hepatocellular carcinoma

Transarterial radioembolization (TARE) with yttrium-90 (90Y) microspheres has been widely adopted for the treatment of HCC. Recent advances in yttrium-90 (90Y) dosimetry have led to durable local responses. Radiation segmentectomy has become a viable alternative to thermal ablation for early-stage HCC (Barcelona Clinic Liver Cancer 0 and A) and has been commonly used as a bridge to transplant. TARE is also commonly used for downstaging to transplant using traditional lobar dosimetry and radiation segmentectomy techniques. Radiation lobectomy has a dual role in local tumor control and induction of contralateral liver lobe hypertrophy as a bridge to resection for patients with an inadequate future liver remnant. TARE continues to provide disease control for patients with limited vascular invasion and may be an alternative to systemic therapy for patients with localized advanced disease. The potential synergy between TARE and immunotherapy has been recognized, and prospective studies evaluating this combination are needed for patients with Barcelona Clinic Liver Cancer B and C HCC.

Antitumor Activity of Metformin Combined with Locoregional Therapy for Liver Cancer: Evidence and Future Directions

This article aimed to examine the effect of metformin use on improving outcomes after liver-directed therapy in patients with HCC and identify future directions with the adjuvant use of and potential therapeutic agents that operate on similar mechanistic pathways. Databases were queried to identify pertinent articles on metformin's use as an anti-cancer agent in HCC. Eleven studies were included, with five pre-clinical and six clinical studies. The mean overall survival (OS) and progression-free survival were both higher in the locoregional therapy (LRT) + metformin-treated groups. The outcome variables, including local tumor recurrence rate, reduction in HCC tumor growth and size, tumor growth, proliferation, migration and invasion of HCC cells, HCC cell apoptosis, DNA damage, and cell cycle arrest, showed favorable outcomes in the LRT + metformin-treated groups compared with LRT alone. This systemic review provides a strong signal that metformin use can improve the tumor response after locoregional therapy. Well-controlled prospective trials will be needed to elucidate the potential antitumor effects of metformin and other mTOR inhibitors.

Yttrium-90 Activity Quantification in PET/CT-Guided Biopsy Specimens from Colorectal Hepatic Metastases Immediately after Transarterial Radioembolization Using Micro-CT and Autoradiography

PURPOSE

To evaluate the yttrium-90 (90Y) activity distribution in biopsy tissue samples of the treated liver to quantify the dose with higher spatial resolution than positron emission tomography (PET) for accurate investigation of correlations with microscopic biological effects and to evaluate the radiation safety of this procedure.

MATERIALS AND METHODS

Eighty-six core biopsy specimens were obtained from 18 colorectal liver metastases (CLMs) immediately after 90Y transarterial radioembolization (TARE) with either resin or glass microspheres using real-time 90Y PET/CT guidance in 17 patients. A high-resolution micro-computed tomography (micro-CT) scanner was used to image the microspheres in part of the specimens and allow quantification of 90Y activity directly or by calibrating autoradiography (ARG) images. The mean doses to the specimens were derived from the measured specimens' activity concentrations and from the PET/CT scan at the location of the biopsy needle tip for all cases. Staff exposures were monitored.

RESULTS

The mean measured 90Y activity concentration in the CLM specimens at time of infusion was 2.4 ± 4.0 MBq/mL. The biopsies revealed higher activity heterogeneity than PET. Radiation exposure to the interventional radiologists during post-TARE biopsy procedures was minimal.

CONCLUSIONS

Counting the microspheres and measuring the activity in biopsy specimens obtained after TARE are safe and feasible and can be used to determine the administered activity and its distribution in the treated and biopsied liver tissue with high spatial resolution. Complementing 90Y PET/CT imaging with this approach promises to yield more accurate direct correlation of histopathological changes and absorbed dose in the examined specimens.

Bilobar Radioembolization Carries the Risk of Radioembolization-Induced Liver Disease in the Treatment of Advanced Hepatocellular Carcinoma: Safety and Efficacy Comparison to Systemic Therapy with Atezolizumab/Bevacizumab

Recommended treatment options for advanced-stage hepatocellular carcinoma (HCC) include systemic therapy (ST) and trans-arterial radioembolization (TARE) with Yttrium-90 (Y90). Before the approval of immune-checkpoint inhibitors, a similar safety profile was reported for TARE and ST with tyrosine kinase inhibitors (TKI). However, whole-liver treatment and underlying cirrhosis were identified as risk factors for potentially lethal radioembolization-induced liver disease (REILD). Therefore, the safety and efficacy of TARE and ST with atezolizumab/bevacizumab were compared in patients with advanced HCC involving at least both liver lobes in a retrospective real-world cohort. In total, 74 patients with new or recurrent advanced-stage HCC (BCLC stage B/C) were included if treated with either bilobar TARE (n = 33) or systemic combination therapy with atezolizumab plus bevacizumab (n = 41). Most patients had compensated liver function (90.5% were classified as Child-Pugh Score A, 73% as ALBI Grade 1) at baseline. Although not significant, patients treated with ST showed a more prolonged overall survival than those treated with Y90 TARE (7.1 months vs. 13.0 months, p = 0.07). While a similar disease control rate could be achieved with bilobar TARE and atezolizumab/bevacizumab, in the TARE group, overall survival was curtailed by the occurrence of REILD. In patients with underlying liver cirrhosis, the liver function at baseline was a predictor for REILD.

Optimal treatment for small HCC (<3 cm): Resection, liver transplantation, or locoregional therapy?

Hepatocellular carcinoma (HCC) remains the most common form of liver cancer, accounting for 90% of all primary liver cancers. Up to 30% of HCC cases could be small (2-3 cm in diameter) at the time of diagnosis with advances in imaging techniques and surveillance programmes. Treating patients with early-stage HCC can be complex and often requires interdisciplinary care, owing to the wide and increasing variety of treatment options, which include liver resection, liver transplantation, and various locoregional therapies offered by interventional radiology and radiation oncology. Decisions regarding the optimal management strategy for a patient involve many considerations, including patient- and tumour-specific characteristics, as well as socioeconomic factors. In this review, we aim to comprehensively summarise the commonly used therapies for single, small HCC (<3 cm), with a focus on the impact of tumour size (<2 cm vs. 2-3 cm), as well as a brief discussion on the cost-effectiveness of the different treatment options.

Surgery and radioembolization of liver tumors

Surgical resection is considered the curative treatment par excellence for patients with primary or metastatic liver tumors. However, less than 40% of them are candidates for surgery, either due to non-modifiable factors (comorbidities, age, liver dysfunction…), or to the invasion or proximity of the tumor to the main vascular requirements, the lack of a future liver remnant (FLR) adequate to maintain postoperative liver function, or criteria of tumor size and number. In these last factors, hepatic radioembolization has been shown to play a role as a presurgical tool, either by hypertrophy of the FLR or by reducing tumor size that manages to reduce tumor staging (term known as "downstaging"). To these is added a third factor, which is its ability to apply the test of time, which makes it possible to identify those patients who present progression of the disease in a short period of time (both locally and at distance), avoiding a unnecessary surgery. This paper aims to review RE as a tool to facilitate liver surgery, both through the experience of our center and the available scientific evidence.

The Hong Kong consensus statements on unresectable hepatocellular carcinoma: narrative review and update for 2021

Background and Objective

Hong Kong, like many parts of Asia, faces a high burden of hepatocellular carcinoma (HCC) caused by high endemic rates of hepatitis B virus infection. Hong Kong clinicians have developed a high level of expertise in HCC treatment across surgical, transarterial, ablative, radiotherapeutic and systemic modalities. This publication summarizes the latest evidence-based recommendations on how these modalities should be used.

Methods

In two meetings held in 2020, a multidisciplinary panel of surgeons, oncologists and interventional radiologists performed a narrative review of evidence on the management of HCC, with an emphasis on treatment of HCC not amenable to surgical resection. Close attention was paid to new evidence published since the previous version of these statements in 2018.

Key Content and Findings

The expert panel has formulated 60 consensus statements to guide the staging and treatment of unresectable HCC. Since the previous version of these statements, considerable additions have been made to the recommendations on use of targeted therapies and immunotherapies because of the large volume of new evidence.

Conclusions

Our consensus statements offer guidance on how to select HCC patients for surgical or non-surgical treatment and for choosing among non-surgical modalities for patients who are not candidates for resection. In particular, there is a need for more evidence to aid physicians in the selection of second-line systemic therapies, as currently most data are limited to patients with disease progression on first-line sorafenib.

Interventional radiological therapies in colorectal hepatic metastases

Colorectal malignancy is the third most common cancer and one of the prevalent causes of death globally. Around 20-25% of patients present with metastases at the time of diagnosis, and 50-60% of patients develop metastases in due course of the disease. Liver, followed by lung and lymph nodes, are the most common sites of colorectal cancer metastases. In such patients, the 5-year survival rate is approximately 19.2%. Although surgical resection is the primary mode of managing colorectal cancer metastases, only 10-25% of patients are competent for curative therapy. Hepatic insufficiency may be the aftermath of extensive surgical hepatectomy. Hence formal assessment of future liver remnant volume (FLR) is imperative prior to surgery to prevent hepatic failure. The evolution of minimally invasive interventional radiological techniques has enhanced the treatment algorithm of patients with colorectal cancer metastases. Studies have demonstrated that these techniques may address the limitations of curative resection, such as insufficient FLR, bi-lobar disease, and patients at higher risk for surgery. This review focuses on curative and palliative role through procedures including portal vein embolization, radioembolization, and ablation. Alongside, we deliberate various studies on conventional chemoembolization and chemoembolization with irinotecan-loaded drug-eluting beads. The radioembolization with Yttrium-90 microspheres has evolved as salvage therapy in surgically unresectable and chemo-resistant metastases.

Single-Compartment Dose Prescriptions for Ablative 90Y-Radioembolization Segmentectomy

BACKGROUND

Yttrium-90 (⁹⁰Y) radioembolization is increasingly being utilized with curative intent. While single-compartment doses with respect to the perfused volume for the complete pathologic necrosis (CPN) of tumors have been reported, the actual doses delivered to the tumor and at-risk margins that leads to CPN have hitherto not been estimated. We present an ablative dosimetry model that calculates the dose distribution for tumors and at-risk margins based on numerical mm-scale dose modeling and the available clinical CPN evidence and report on the necessary dose metrics needed to achieve CPN following ⁹⁰Y-radioembolization.

METHODS

Three-dimensional (3D) activity distributions (MBq/voxel) simulating spherical tumors were modeled with a 121 × 121 × 121 mm³ soft tissue volume (1 mm³ voxels). Then, 3D dose distributions (Gy/voxel) were estimated by convolving 3D activity distributions with a ⁹⁰Y 3D dose kernel (Gy/MBq) sized 61 × 61 × 61 mm³ (1 mm³ voxels). Based on the published data on single-compartment segmental doses for the resected liver samples of HCC tumors showing CPN after radiation segmentectomy, the nominal voxel-based mean tumor dose (DmeanCPN), point dose at tumor rim (DrimCPN), and point dose 2 mm beyond the tumor boundary (D2mmCPN), which are necessary to achieve CPN, were calculated. The single-compartment dose prescriptions to required achieve CPN were then analytically modeled for more general cases of tumors with diameters dt = 2, 3, 4, 5, 6, and 7 cm and with tumor-to-normal-liver uptake ratios T:N = 1:1, 2:1, 3:1, 4:1, and 5:1.

RESULTS

The nominal case defined to estimate the doses needed for CPN, based on the previously published clinical data, was a single hyperperfused tumor with a diameter of 2.5 cm and T:N = 3:1, treated with a single-compartment segmental dose of 400 Gy. The voxel-level doses necessary to achieve CPN were 1053 Gy for the mean tumor dose, 860 Gy for the point dose at the tumor boundary, and 561 Gy for the point dose at 2 mm beyond the tumor edge. The single-compartment segmental doses necessary to satisfy the criteria for CPN in terms of the mean tumor dose, point dose at the tumor boundary, and the point dose at 2 mm beyond the tumor edge were tabulated for a range of tumor diameters and tumor-to-normal-liver uptake ratios.

CONCLUSIONS

The analytical functions that describe the relevant dose metrics for CPN and, more importantly, the single-compartment dose prescriptions for the perfused volume needed to achieve CPN are reported for a large range of conditions in terms of tumor diameters (1-7 cm) and T:N uptake ratios (2:1-5:1).

Local Therapies for Hepatocellular Carcinoma and Role of MRI-Guided Adaptive Radiation Therapy

Hepatocellular carcinoma (HCC) is the most common liver tumor, with a continually rising incidence. The curative treatment for HCC is surgical resection or liver transplantation; however, only a small portion of patients are eligible due to local tumor burden or underlying liver dysfunction. Most HCC patients receive nonsurgical liver-directed therapies (LDTs), including thermal ablation, transarterial chemoembolization (TACE), transarterial radioembolization (TARE), and external beam radiation therapy (EBRT). Stereotactic ablative body radiation (SABR) is a specific type of EBRT that can precisely deliver a high dose of radiation to ablate tumor cells using a small number of treatments (or fractions, typically 5 or less). With onboard MRI imaging, MRI-guided SABR can improve therapeutic dose while minimizing normal tissue exposure. In the current review, we discuss different LDTs and compare them with EBRT, specifically SABR. The emerging MRI-guided adaptive radiation therapy has been reviewed, highlighting its advantages and potential role in HCC management.

Advances in Radiation Therapy for Primary Liver Cancer

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

Maximum tumor-absorbed dose measured by voxel-based multicompartmental dosimetry as a response predictor in yttrium-90 radiation segmentectomy for hepatocellular carcinoma

OBJECTIVE

Advances in hepatic radioembolization are based on a selective approach with radical intent and the use of multicompartment dosimetric analysis. The objective of this study is to assess the utility of voxel-based dosimetry in the quantification of actual absorbed doses in radiation segmentectomy procedures and to establish cutoff values predictive of response.

METHODS

Ambispective study in hepatocarcinoma patients treated with radiation segmentectomy. Calculated dosimetric parameters were mean tumor-absorbed dose, maximum tumor AD, minimal tumor AD in 30, 50, and 70% of tumor volume and mean AD in non-tumor liver. The actual absorbed dose (aAD) was calculated on the Y-90-PET/CT image using 3D voxel-based dosimetry software. To assess radiological response, localized mRECIST criteria were used. The objective response rate (ORR) was defined as CR or PR.

RESULTS

Twenty-four HCC patients, BCLC 0 (5), A (17) and B (2) were included. The mean yttrium-90 administered activity was 1.38 GBq in a mean angiosome volume of 206.9 cc and tumor volume 56.01 cc. The mean theoretical AD was 306.3 Gy and aAD 352 Gy. A very low concordance was observed between both parameters (rho_c 0.027). ORR at 3 and 6 m was 84.21% and 92.31%, respectively. Statistically significant relationship was observed between the maximum tumor-absorbed dose and complete radiological response at 3 m (p 0.022).

CONCLUSION

A segmental approach with radical intention leads to response rates greater than 90%, being the tumor maximum absorbed dose the dosimetric parameter that best predicts radiological response in voxel-based dosimetry.

Prior ablation and progression of disease correlate with higher tumor-to-normal liver 99mTc-MAA uptake ratio in hepatocellular carcinoma

PURPOSE

Factors affecting tumor-to-normal tissue ratio (T:N) have implications for patient selection, dosimetry, and outcomes when considering radioembolization for HCC. This study sought to evaluate patient, disease specific, and technical parameters that predict T:N as measured on planning pre-⁹⁰Y radioembolization ^99mTc-MAA scintigraphy for hepatocellular carcinoma (HCC).

METHODS

^99mTc-MAA hepatic angiography procedures with SPECT/CT over a 4-year period were reviewed. Data recorded included patient demographics, details of underlying liver disease, tumor size, history of prior treatments for HCC and technical parameters from angiography. Anatomic-based segmentation was performed in 93 cases for measurement of tumor and perfused liver volumes and SPECT counts. T:N were calculated and correlated with collected variables.

RESULTS

Mean calculated T:N was 2.52. History of prior ablation was significantly correlated with higher T:N (mean 3.39 vs 2.24, p = 0.003). Cases in which mapping was being performed for treatment of disease progression was significantly correlated with higher T:N (mean 3.35 vs 2.14, p = 0.001). Larger tumor size trended toward lower T:N (p = 0.052).

CONCLUSION

Patients with history of ablation and those undergoing treatment for disease progression have higher T:N and, therefore, could be considered for radioembolization preferentially over alternative treatments.

Clinical, dosimetric, and reporting considerations for Y-90 glass microspheres in hepatocellular carcinoma: updated 2022 recommendations from an international multidisciplinary working group

PURPOSE

In light of recently published clinical reports and trials, the TheraSphere Global Dosimetry Steering Committee (DSC) reconvened to review new data and to update previously published clinical and dosimetric recommendations for the treatment of hepatocellular carcinoma (HCC).

METHODS

The TheraSphere Global DSC is comprised of health care providers across multiple disciplines involved in the treatment of HCC with yttrium-90 (Y-90) glass microsphere-based transarterial radioembolization (TARE). Literature published between January 2019 and September 2021 was reviewed, discussed, and adjudicated by the Delphi method. Recommendations included in this updated document incorporate both the results of the literature review and the expert opinion and experience of members of the committee.

RESULTS

Committee discussion and consensus led to the expansion of recommendations to apply to five common clinical scenarios in patients with HCC to support more individualized efficacious treatment with Y-90 glass microspheres. Existing clinical scenarios were updated to reflect recent developments in dosimetry approaches and broader treatment paradigms evolving for patients presenting with HCC.

CONCLUSION

Updated consensus recommendations are provided to guide clinical and dosimetric approaches for the use of Y-90 glass microsphere TARE in HCC, accounting for disease presentation, tumor biology, and treatment intent.

Yttrium-90 Radioembolization: Current Indications and Outcomes

BACKGROUND

Radioembolization (RE) with 90Yttrium (Y90) has generally been used to treat patients with advanced disease. Recent data suggest, however, that RE is also safe and feasible to treat patients with early or intermediate stage disease. We herein review the current evidence regarding the use of RE with Y90 for patients with HCC.

METHODS

A comprehensive review of the literature was performed using MEDLINE/PubMed and Web of Science databases with a search end date of August 1, 2022.

RESULTS

Patients with HCC are often treated according to the BCLC staging system. Among patients with early-stage HCC (BCLC A), intermediate-stage HCC (BCLC B), and advanced-stage HCC (BCLC C), RE with Y90 has demonstrated promising results with comparable overall survival, time to disease progression, and radiological response compared with other standard of care treatment modalities. Moreover, Y90 RE can be used as a downstaging treatment modality for patients with advanced HCC who have a disease burden that is initially outside LT criteria. Radiation lobectomy (RL) has been described as a treatment modality with the intent of treating the ipsilateral liver that harbors the HCC, while also causing compensatory hypertrophy of the future liver remnant (FLR).

CONCLUSION

While initially considered as a palliative option for HCC patients, Y90 RE has emerged as an important part of the multi-modality care of patients with HCC across a wide spectrum of clinical indications.