EANM procedure guideline for the treatment of liver cancer and liver metastases with intra-arterial radioactive compounds

Ultrasound contrast microbubbles to predict the microsphere distribution during transarterial radioembolization with holmium microspheres, an in vitro proof of concept study

Transarterial radioembolization (TARE) is an established treatment method for non-resectable liver tumors. One of the challenges of the approach is the accurate prediction of the microsphere biodistribution in the liver. We propose to use ultrasound contrast microbubbles as holmium microsphere precursors, which allows real-time prediction of the microsphere trajectories and biodistribution using dynamic contrast-enhanced ultrasound (DCE-US). The immediate goal in this in vitro study was to investigate the predictive capabilities of microbubbles as microsphere precursors. The study was conducted in an experimental in vitro model which represents the bifurcating right branch of the hepatic artery. A controlled injection of experimental BR-14 ultrasound contrast microbubbles and non-radioactive holmium-165 microspheres was performed in separate consecutive experiments in an arterial flow phantom. The microbubbles and microspheres were collected separately at the outlets of the phantom and counted using a Coulter counter to determine their distribution over the different outlets. The flow profile, the injection velocity, and the catheter position were monitored during the measurements to ensure stability. The results showed a good correlation between the microbubble and the microsphere distributions (p = 0.0038, r = 0.88) measured at the outlets. Differences in the distributions could be attributed to the characteristics of microbubbles and microspheres alone (e.g. particle size and concentration), since critical parameters were kept stable between the two experiments. The current in vitro study provides confidence that the microsphere biodistribution can be predicted using contrast microbubbles. The comparison provided by this study forms a foundation for the development of a DCE-US guided TARE treatment.

Comparative voxel-based dosimetry with pre-treatment Tc-99m SPECT/CT and post-treatment Y-90 PET/MRI for radioembolization with Y-90 microspheres

PURPOSE

The aim of this study was to investigate the differences between voxel-based dosimetry and the mean absorbed doses calculated with pre-treatment Tc-99 m-MAA SPECT/CT and post-treatment Y-90 PET/MR images. We also sought to present a detailed comparison of dose-volume histograms (DVHs) calculated from pre- and post-treatment imaging.

METHODS

A total of 47 treatments and 41 patients were included in the analysis as six of the treatments were retreatments of the six patients. Multicompartment and voxel-based dosimetry were performed with pre-treatment Tc-99m-MAA SPECT/CT and Y-90 PET/MRI. Correlation coefficients between the two imaging methods for the mean absorbed dose of tumor, whole liver normal tissue, perfused normal tissue, T/N ratio and tumor D10, D50 and D90 values were calculated. Additionally, differences between these values were also evaluated with Bland-Altman plots.

RESULTS

Pre-treatment Tc-99m-MAA SPECT/CT accurately predicted the dose values for healthy liver parenchyma calculated with Y-90 PET/MRI but showed lower accuracy in predicting T/N ratio and tumor doses. There were significant variations in tumor-absorbed doses for both glass and resin microspheres. Additionally, D90 values were higher when calculated with SPECT/CT than with PET/MRI, whereas D10 values were higher in PET/MRI compared to SPECT/CT.

CONCLUSION

The findings in our study suggest that Tc-99m-MAA SPECT/CT had higher accuracy in predicting the dose to the healthy liver parenchyma compared to the tumor, maintaining its importance in treatment planning.

Assessment of Hypoxia Before Radioembolization Treatment With 18 F-FMISO PET : ARTE-MISO Trial

BACKGROUND

Transarterial radioembolization (TARE) is a therapeutic option for patients with liver tumors. However, factors responsible for treatment resistance in TARE remain largely unknown. In this study, we aimed to investigate the role of hypoxia in the treatment response of liver tumors using 18 F-FMISO PET imaging before TARE.

PATIENTS AND METHODS

This single-center prospective study included 25 patients with primary or metastatic liver tumors imaged with 18 F-FMISO PET/CT before TARE and treated with 90 Y resin microspheres. Posttreatment response was assessed with 18 F-FDG PET imaging. Hypoxia status was evaluated by calculating the tumor-to-muscle (T/M) and tumor-to-blood pool (T/BP) ratios. Absorbed dose metrics were derived from 90 Y PET/MRI imaging post-procedure. Lesions were categorized by response as complete responders (CR), partial responders (PR), stable disease (SD), and progressive disease (PD). Statistical analyses included ROC curve analysis, χ2 tests, and regression models to determine predictors of treatment response.

RESULTS

Among 25 patients (mean age: 60.4 ± 12 y, 56% males), 54 18 F-FDG-avid lesions were evaluated. The median absorbed dose (Dmean) was 114.8 Gy for CR, 98.9 Gy for PR, 56.7 Gy for SD, and 78.3 Gy for PD. Significant differences in Dmean ( P = 0.013) and T/BP ratios ( P = 0.011) were observed between responder and nonresponder groups. High Dmean lesions (>89 Gy) had a response rate of 86%, compared with 56% in low Dmean lesions. Hypoxic lesions (T/BP >1.29) showed a 57% response rate, while non-hypoxic lesions (T/BP <1.29) showed a 91% response rate. In combined analyses, while non-hypoxic/high Dmean lesions had the highest response rates (93%), hypoxic/low-dose had the lowest response rate (39%).

CONCLUSIONS

In this study, we have observed that both mean absorbed radiation dose and hypoxia status are significant predictors of response to treatment after radioembolization of liver tumors. While larger studies are needed to confirm these findings, this pilot study may pave the way for further personalized treatments to achieve better results for radioembolization.

Eco-Friendly Approaches in Oncology: Developing Holmium (166Ho) Glass Microspheres for Hepatocellular Radioembolization

Using recycled materials is increasingly recognized as a crucial strategy in today's global context. The production of glass on a global scale, estimated at approximately 209 million tons annually, underscores the urgent necessity to identify alternative applications for this material. In this milieu, the adoption of recycled glass for applications conducive to health emerges as a significant opportunity, offering dual advantages: mitigating the global surplus of glass and enhancing public health outcomes. In the realm of diseases, oncology, and hepatocellular carcinoma stand out due to their extensive costs and detrimental impact on health. Consequently, this research has been directed toward developing, comprehensively characterization, and in vivo assessment of Ho (Ho-166) holmium-166 doped glass microspheres derived from recycled glass. The findings confirmed the successful formation of these microspheres, marked by a high degree of holmium doping. Moreover, the studies revealed a significant accumulation of the microspheres in the liver, alongside a lack of toxicological effects. Collectively, these results strongly support the potential of recycled glass as a valuable resource for fabricating holmium-doped glass microspheres, offering a promising avenue for liver cancer treatment.

Holmium-166 Radioembolization Is a Safe and Effective Locoregional Treatment for Primary and Secondary Liver Tumors: A Systematic Review and Meta-Analysis

BACKGROUND/OBJECTIVES

This systematic review and meta-analysis evaluated the effectiveness and the safety of transarterial radioembolization using Holmium-166 microspheres (Ho-166-TARE) for the treatment of primary and secondary liver tumors. The aim of the study was to offer a detailed analysis of clinical outcomes and the potential benefits of this innovative therapy.

METHODS

The study was conducted according to the PRISMA 2020 guidelines. The systematic search was performed in five databases in November 2023 and updated in June 2024. All 16 eligible studies were original research that evaluated Ho-166-TARE. The endpoints analyzed were disease control rate (DCR), overall survival (OS), progression-free survival (PFS), clinical and laboratory adverse events, healthy-liver- and tumor-liver-absorbed doses. The risk of bias was assessed using the MINORS checklist.

RESULTS

The pooled overall disease control rate (DCR) was 72% (95% CI, 46-89%); by mRECIST, it was 93% (95% CI, 71-99%); and by RECIST 1.1, it was 54% (95% CI, 22-83%) at 3-month follow-up. Overall survival (OS) at 3, 6, 12, and 30 months was 98%, 89%, 74%, and 39%, respectively. Severe clinical adverse events were minimal, although some patients showed elevated GGT levels and lymphocytopenia. Tumor-absorbed doses were nearly three times higher than those in healthy liver tissue.

CONCLUSIONS

These findings suggest that Ho-166-TARE is a safe and effective locoregional treatment option for liver tumors, especially in cases where systemic therapy alone is insufficient or surgical resection is not feasible. Further studies are needed to investigate tumor-specific response, optimize dosimetry strategies, and establish standardized protocols for long-term outcome assessment.

The relationship between yttrium-90 glass microspheres specific activity, particle density and treatment outcomes in HCC and mCRC

PURPOSE

To investigate relationships between treatment week, relative to Ytrrium-90 (90Y) glass microsphere calibration (i.e., specific activity and particle density), and outcomes for hepatocellular carcinoma (HCC) or colorectal cancer liver metastasis (mCRC).

METHODS

Multinational, multicenter study TARGET (retrospective; n = 209 HCC patients) was combined with EPOCH (phase III trial; n = 428 mCRC patients). Efficacy included overall response rate (ORR), overall survival (OS), progression-free survival (PFS), hepatic PFS, and tumour marker response rates. Safety included clinical and laboratory toxicity. Retrospective multicompartment dosimetry, tumour and normal tissue absorbed dose were available for TARGET; single compartment dosimetry was available for EPOCH.

RESULTS

No efficacy relationship was found relative to treatment week for TARGET or EPOCH. mRECIST ORR in TARGET for weeks 1 and 2 were 74/125 (59.2%) and 55/84 (65.5%), and by RECIST 1.1 in EPOCH were 54/142 (38.0%) and 15/43 (34.9%), respectively (p > 0.05). Median OS for TARGET weeks 1 and 2 were 21.4 and 20.3 months (p = 0.07), and in EPOCH were 14.9 and 16.4 months, respectively (p = 0.37). No difference in the TARGET primary endpoint of hyperbilirubinemia was noted for weeks 1 and 2, odds ratio 0.64, p = 0.59. TARGET ≥ grade 3 device-related adverse events (AEs) for weeks 1 (16.8%) and 2 (26.2%) were not significantly different (p = 0.11). EPOCH rates of ≥ grade 3 asthenia for weeks 1 (9.2%) and 2 (23.3%) were statistically different (p = 0.01).

CONCLUSIONS

No efficacy treatment benefit for week 2 versus week 1 was observed in TARGET or EPOCH, but week 2 treatment trended towards a higher rate and severity of specific AEs.

Transarterial Radioembolization in the TACOME Trial: Dosimetric Analysis and Clinical Features in Predicting Response and Overall Survival

In this multicenter retrospective study, we aimed to analyze the dose-response and survival relationships and estimate the tumor absorbed radiation dose required to achieve response in colorectal cancer liver metastases treated with 90Y glass microspheres. Methods: Patients with metastatic colorectal cancer treated with 90Y glass microspheres were included in this retrospective study. Mean perfused volume, mean estimated perfused volume absorbed dose, mean estimated tumor absorbed dose (ETAD), mean estimated perfused normal liver absorbed dose, and mean estimated whole liver absorbed dose were calculated using [99mTc]-macroaggregated albumin SPECT images. Treatment to response was evaluated by [18F]-FDG PET images. Results: In total, 176 patients (112 men and 64 women) were included in the analysis. A strong correlation was found between mean ETAD and response to treatment (P = 0.001). The cutoff values to predict a response were calculated as 109 Gy (sensitivity, 68%; specificity, 73%; area under the curve, 0.728; P = 0.001) for mean estimated perfused volume absorbed dose and 152 Gy (sensitivity, 93%; specificity, 89%; area under the curve, 0.945; P = 0.001) for mean ETAD. The median overall survival (OS) of patients with a mean ETAD higher than 152 Gy was significantly longer than that of the remaining patients, at 18.1 mo (95% CI, 15.7-20.4 mo) versus 12.8 mo (95% CI, 10.6-15.0 mo; P = 0.030). Further analysis using maximally selected rank statistics to better predict OS showed that patients with a minimum mean ETAD of 203 Gy had OS 6.4 mo longer than the OS of those with a lower mean ETAD (P = 0.022). Conclusion: A mean radiation dose to the tumor of at least 152 Gy may predict a metabolic response. Although a threshold of 152 Gy predicted longer OS, a mean ETAD of 203 Gy, when achievable, predicted even longer OS than found for those with a mean ETAD of less than 203 Gy.

Dosimetric optimization and evaluation of hepatocellular carcinoma treatment effect prediction in Y-90 radioembolization

BACKGROUND

Liver transarterial radioembolization (TARE) with 90Y microspheres is a common treatment for hepatocellular carcinoma (HCC). A pre-treatment SPECT/CT dosimetric study is performed using 99mTc macroaggregated albumin, followed by PET-based dosimetry to assess dose distribution of 90Y. Recent studies show a significant correlation between absorbed doses and treatment outcomes in terms of radiological response, adverse events and overall survival. This study aims to present optimized TARE dosimetry protocols and assess outcome predictions according to voxel-based dosimetry.

METHODS

Dosimetry protocols were refined according to EANM guidelines using the Planet Dose software. Pre-treatment dosimetry was conducted for all patients while post-treatment dosimetry was performed for patients treated after the installation of a new PET/CT system. Statistical analysis was employed to evaluate predictors of complete radiological response (CR) and survival outcomes.

RESULTS

133 HCC patients treated with 90Y microspheres (95 resin, 38 glass) at single institution were analyzed. ROC curve analysis for resin microspheres indicated a dose threshold of 233.2 Gy (AUC = 0.62) as the best predictor for CR, with higher CR rates in patients receiving this dose. No lung toxicity was noted nor correlation was found between doses to normal liver tissue and adverse events.

CONCLUSIONS

Lesion absorbed dose is a significant predictor of CR in resin microspheres, with a mean dose of at least 233.2 Gy leading to better oncologic response rates. The absence of correlation between healthy liver tissue dose and adverse events suggests the potential for further increasing the dose to achieve event better outcomes in future protocols.

Tumoricidal dosing approach with parenchymal sparing using voxel-based dosimetry in 90Y glass microspheres treatment of hepatocellular carcinoma

OBJECTIVE

We aimed to evaluate the effect of tumor absorbed doses (TAD) on treatment response in patients with hepatocellular cancer (HCC) treated with 90Y glass microspheres. We aimed to define a cutoff value for complete response (CR).

METHODS

The voxel-based dosimetry for the treatment of 66 HCC lesions in 56 patients was analyzed retrospectively. Nineteen patients had BCLC A, 23 patients had BCLC B, and 14 patients had BCLC C disease. Treatments were grouped as selective (radiation segmentectomy and super-selective segmentectomy, n:49) and nonselective (palliative treatments for tumors occupying >2 segments, n:17). Treatment response was evaluated by mRECIST criteria, defined as CR, partial response (PR), stable lesion (SL), and progressive lesion (PL). TAD associated with CR was analyzed.

RESULTS

TAD was 525 ± 222 Gy in our cohort. Fifteen lesions had CR, 28 had PR, eight remained stable, and 15 lesions progressed. CR, PR, SL, and PL rates for selective vs. nonselective treatments were 31, 42, 12, and 14% vs. 0, 41, 11, and 47% for nonselective treatments, respectively (P:0.01). TAD was significantly associated with treatment response. Receiver operating characteristic analysis showed TAD > 475 Gy predicted CR with 100% sensitivity and 68% specificity (area under the curve = 0.83, P < 0.001). Overall survival declined as treatment response deteriorated. None of the patients had radiation-induced liver dysfunction on follow-up (6-21 months).

CONCLUSION

Higher TAD is crucial for CR. Segmentectomy with TAD > 475 Gy is associated with favorable response and better survival in HCC patients. Even for palliative treatments, as high as reasonably tolerated doses must be applied to achieve a favorable response.

Post-Y90 PET Dosimetry

Transarterial radioembolization with yttrium-90 is widely used to treat unresectable liver cancer by delivering radiation directly to tumors. While post-treatment imaging generally relies on single-photon emission computed tomography (SPECT) and SPECT/computed tomography (CT), lower signal-to-noise ratio and spatial resolution limit its application. PET/CT and PET/MR imaging have proven to provide more effective image quality, yielding clearer images for accurate dose quantification and correlation with treatment response. PET-based imaging is crucial for refining dose-response and dose-toxicity relationships in personalized dosimetry, although its limited availability challenges its widespread use.

Health-related quality of life in patients with unresectable hepatocellular carcinoma treated with SIRT and nivolumab: a sub-analysis of the NASIR-HCC trial

BACKGROUND

The health-related quality of life (HRQoL) impact of therapies for hepatocellular carcinoma (HCC) influences decision-making and treatment outcomes. The present study reports HRQoL results from NASIR-HCC, a single-arm study of selective internal radiation therapy (SIRT) with Y90 resin microspheres followed by nivolumab for unresectable HCC.

METHODOLOGY

Participants completed the EQ-5D-3 L, EQ-VAS, and FACT-Hep at baseline and on the first day of each nivolumab cycle. Linear mixed-effect models were used to calculate changes in outcomes in participants with the baseline and ≥ 1 follow-up measurement. Changes were assessed for clinical meaningfulness versus published minimally important differences.

RESULTS

Thirty-two patients from NASIR-HCC were included. Completion rates exceeded 70% at 62% of time points. Across EQ-5D-3 L domains, minimal changes were reported. Most patients had no problems at almost all time points. Mean index values were 0.864 at baseline and 0.763 in cycle 8, but this difference was not clinically meaningful. The small EQ-VAS increase, from 74.8 at baseline to 75.9 in cycle 8, was also not clinically meaningful. The various FACT scales remained stable, although transient but not clinically meaningful declines occurred for some scales. The median time to deterioration was 5.5 months for the FACT-Hep score.

CONCLUSIONS

Combining SIRT with nivolumab did not compromise HRQoL in patients with unresectable HCC. Study results were limited by the small number of patients but, combined with the previously reported clinical outcomes, suggested that the treatment combination deserves further consideration in this difficult-to-treat population.

TRIAL REGISTRATION NUMBER/DATE OF REGISTRATION

NCT03380130. First submitted on 2017-10-20; https://clinicaltrials.gov/study/NCT03380130 .

Radioembolization for Hepatocellular Carcinoma: a Comparison on Dual-phase Cone-beam CT, Contrast-enhanced CT (CECT) and 99mTc-macroaggregated albumin-SPECT/CT in predicting final distribution volumes and dosimetry of the post-embolization 90Y PET/CT

PURPOSE

Personalized treatment schemes are being systematically applied to ensure best treatment outcome in oncologic patients. This is true also for personalized dosimetry in transarterial radioembolization (TARE) in hepatocellular carcinoma (HCC) patients. Precise and detailed volumetric and functional data derived from radiological and nuclear imaging methods are essential for personalized dosimetry. We sought to evaluate accuracy of dual-phase cone-beam CT (CBCT) in comparison to pre-treatment contrast-enhanced CT (CECT), and 99mTc-macroaggregated albumin-SPECT/CT ([99mTc]MAA SPECT/CT) to predict and assess the efficacy of TARE based on post-treatment 90Y PET/CT.

MATERIAL AND METHODS

Thirty consecutive patients with HCC treated with TARE were included. Intraprocedural dual-phase CBCT acquisition protocol was developed to distinguish tumor volume in the early arterial phase and perfused volume of non-affected liver in the late arterial phase. Volumetric data obtained from pre-treatment CECT, dual-phase CBCT and [99mTc]MAA SPECT/CT were compared to post-treatment 90Y PET/CT considered the standard reference. Treatment simulations for final calculated dose from the different imaging derived volumes were then compared to post-treatment 90Y PET/CT.

RESULTS

CBCT resulted as the most accurate method in predicting tumor- (R2 0.88) and perfused volumes (R2 0.82). Dosimetry prediction planning performed on derived volumes from the different methods did not show significant difference (p < 0.05), yet highest concordance with 90Y PET/CT data was observed with dual-phase CBCT.

CONCLUSION

Our study shows that dual-phase CBCT acquisition is a novel alternative method for correctly and safely administering more accurate and defined doses during TARE.

CLINICALTRIALS

gov ID: NCT03981497.

166Ho-RadioEmbolizaTiOn Using personalized prediCtive dosimetry in patients with Hepatocellular carcinoma: A prospective, single-centre study (RETOUCH)

BACKGROUND AND AIMS

Holmium-166 (166Ho) radioembolization could offer a more individualized approach in terms of imaging and dosimetry. We aim to evaluate the feasibility and safety of 166Ho selective internal radiation therapy (SIRT) using a higher tumour dose than previously administered determined by 166Ho-scout as a surrogate marker in HCC patients.

METHODS

This is an open-label, prospective, non-randomized, single-centre pilot study that included patients with HCC that received 166Ho-SIRT if the work-up using 166Ho-scout showed a tumour-absorbed dose ≥150 Gy, a non-tumoural liver absorbed dose less than 60 Gy and a lung absorbed dose less than 30 Gy. Primary endpoints were feasibility and safety-toxicity profiles at 24-48 h and 1 month. Overall response rates (ORR) at 3 months (mRECIST, RECIST 1.1 and metabolic response by FDG and choline PET CT) and time to progression (TTP) represented the secondary endpoints.

RESULTS

Fifteen patients with large tumours (mean diameter 55.67 ± 28.42 mm) received 17 166Ho-SIRT treatments between July 2020 and June 2022. All the attempted treatments were accomplished. Mean administered tumour dose was 183.18 ± 71.71 Gy, while non-tumour liver dose was 30.29 ± 14.56 Gy. Median time of follow-up was 12 months (IQR 9-16). Only grade 1-2 clinical and biological AEs were observed. There were no liver decompensations. At 3 months, objective response was achieved for all target lesions (CR 78.57%, PR 21.43% according to mRECIST). Median TTP was 18.8 (range 2.9; n.e.) months.

CONCLUSION

Personalized 166Ho-SIRT with a tumour delivered dose ≥150 Gy was feasible and safe for HCC patients with promising response rates.

Prediction of left lobe hypertrophy with voxel-based dosimetry using integrated Y-90 PET/MRI after radioembolization of liver tumors with Y-90 microspheres

PURPOSE

The aim of this study was to investigate the relationship between voxel-based dosimetric variables derived from Y-90 PET/MRI and hypertrophy observed in the left lobe after radioembolization and to investigate if there is any difference in hypertrophy induced by glass versus resin microspheres.

METHODS

Voxel-based dosimetry-derived variables and their relationship with the change of the standardized future liver remnant (ΔFLR) was investigated with linear regression models. To compare and evaluate the discriminatory power of the dosimetric variables, ROC analyses were utilized. ΔFLR and kinetic growth rate (KGR) induced with glass and resin microspheres were compared using the Mann-Whitney U test.

RESULTS

In this retrospective study, data of the 40 patients treated with Y-90 microspheres were evaluated. Among the several dosimetric variables, the mean perfused volume normal tissue dose (pDnorm), perfused normal tissue V90 (pV90), and pV100 values for glass microspheres; and the mean whole liver normal tissue dose (Dnorm), pDnorm, whole liver normal tissue V30 (nV30), nV40, and pV40 for resin microspheres had the highest relationship with ΔFLR. In the ROC analysis for glass microspheres, the optimal cut-offs to predict ΔFLR > 5% were 60.55 Gy for Dnorm, 94.21 Gy for pDnorm, 28.07% for pV90, and 24.98% for pV100. For resin microspheres, corresponding values were 23.20 Gy for Dnorm, 37.40 Gy for pDnorm, 31.50% for nV30, 24.50% for nV40, and 43.60% for pV40. No significant difference was observed between glass and resin microsphere-induced median ΔFLR, KGR values and atrophy of the right lobe.

CONCLUSION

Following Y-90 radioembolization therapy with glass and resin microspheres applied to the right lobe of the liver, ΔFLR is correlated with pDnorm and Dnorm, but is also significantly related to various nV and pV values. In addition, the hypertrophy and kinetic growth rates observed with glass and resin microspheres were largely similar.

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.

Usefulness of multiphasic MRI in assessing suitability for SIRT in treatment of liver malignancies

AIM

To evaluate the predictive value of multiphasic magnetic resonance imaging (MRI) in identifying liver tumor perfusion characteristics and to compare it with hepatic artery perfusion scintigraphy findings in patients considered for selective internal radiation therapy (SIRT) with yttrium-90 (Y-90).

METHODS

This study included 93 patients diagnosed with primary or secondary liver cancer between May 2021 and February 2024, comprising 47 patients (27 M/20F) deemed unsuitable for SIRT and 46 patients (26 M/20F) eligible for SIRT. The relationship between multiphasic MRI and scintigraphy findings in determining perfusion of tumors was analyzed. Predictive performance was evaluated with receiver operating characteristic (ROC) analysis, and the optimal cut-off values were determined using the Youden index.

RESULTS

The SIRT unsuitable group had a lower frequency of intratumoral arterial phase hyperenhancement(APHE) (40.43% vs. 69.57%, p = 0.042), presence of hyperintensity on T2 sequence (72.34% vs. 95.65%, p = 0.026), lower lesion intensity in the portal phase (p = 0.033), and a lower lesion-to-liver intensity ratio in the portal phase (≤ 0.97, p = 0.011). The absence of intratumoral APHE [p = 0.049, AUC (95% CI) = 0.646 (0.508-0.783)] and a lesion-to-liver intensity ratio in the portal phase with a cut-off value of ≤ 0.97 [p = 0.011, AUC (95% CI) = 0.689 (0.564-0.815)] were significant predictors of SIRT unsuitability.

CONCLUSION

Both the absence of intratumoral APHE and a lower lesion-to-liver intensity ratio in the portal phase were significant predictors of SIRT unsuitability.

Preparation of iodine-131 labeled Polyvinyl alcohol-collagen microspheres for radioembolization therapy of liver tumors

Transarterial radioembolization using radionuclide-labeled microspheres has shown efficacy in the treatment of hepatocellular carcinoma (HCC). In this study, a novel formulation of Polyvinyl alcohol-collagen microspheres (PCMs) with an optimal settling rate is developed. Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) analyses confirm that the PCMs have uniform morphology with diameters ranging from 20 to 30 μm. These microspheres are successfully labeled with 131I, exhibiting good in vitro stability. Subsequently, 131I-labeled PCMs are administered via the hepatic artery into rats with orthotopic HCC, leading to a significant increase in median overall survival (p < 0.05). Single photon emission computed tomography (SPECT/CT) imaging and immunohistochemical assessments demonstrate precise biodistribution and stable retention of 131I-PCMs in the liver for up to 14 days. Magnetic resonance imaging (MRI) further reveals the inhibition of tumor growth following 131I-PCM treatment. In summary, the 131I-PCMs display high radiolabeling efficiency, stability, and a promising radioembolization effect in the orthotopic HCC rodent model, highlighting their potential for use in interventional cancer therapy.

CT-free attenuation and Monte-Carlo based scatter correction-guided quantitative 90Y-SPECT imaging for improved dose calculation using deep learning

BACKGROUND

This work aimed to develop deep learning (DL) models for CT-free attenuation and Monte Carlo-based scatter correction (AC, SC) in quantitative 90Y SPECT imaging for improved dose calculation.

METHODS

Data of 190 patients who underwent 90Y selective internal radiation therapy (SIRT) with glass microspheres was studied. Voxel-level dosimetry was performed on uncorrected and corrected SPECT images using the local energy deposition method. Three deep learning models were trained individually for AC, SC, and joint ASC using a modified 3D shifted-window UNet Transformer (Swin UNETR) architecture. Corrected and unorrected dose maps served as reference and as inputs, respectively. The data was split into train set (~ 80%) and unseen test set (~ 20%). Training was conducted in a five-fold cross-validation scheme. The trained models were tested on the unseen test set. The model's performance was thoroughly evaluated by comparing organ- and voxel-level dosimetry results between the reference and DL-generated dose maps on the unseen test dataset. The voxel and organ-level evaluations also included Gamma analysis with three different distances to agreement (DTA (mm)) and dose difference (DD (%)) criteria to explore suitable criteria in SIRT dosimetry using SPECT.

RESULTS

The average ± SD of the voxel-level quantitative metrics for AC task, are mean error (ME (Gy)): -0.026 ± 0.06, structural similarity index (SSIM (%)): 99.5 ± 0.25, and peak signal to noise ratio (PSNR (dB)): 47.28 ± 3.31. These values for SC task are - 0.014 ± 0.05, 99.88 ± 0.099, 55.9 ± 4, respectively. For ASC task, these values are as follows: -0.04 ± 0.06, 99.57 ± 0.33, 47.97 ± 3.6, respectively. The results of voxel level gamma evaluations with three different criteria, namely "DTA: 4.79, DD: 1%", "DTA:10 mm, DD: 5%", and "DTA: 15 mm, DD:10%" were around 98%. The mean absolute error (MAE (Gy)) for tumor and whole normal liver across tasks are as follows: 7.22 ± 5.9 and 1.09 ± 0.86 for AC, 8 ± 9.3 and 0.9 ± 0.8 for SC, and 11.8 ± 12.02 and 1.3 ± 0.98 for ASC, respectively.

CONCLUSION

We developed multiple models for three different clinically scenarios, namely AC, SC, and ASC using the patient-specific Monte Carlo scatter corrected and CT-based attenuation corrected images. These task-specific models could be beneficial to perform the essential corrections where the CT images are either not available or not reliable due to misalignment, after training with a larger dataset.

Long-term outcomes of Yttrium-90 transarterial radioembolization for patients with hepatocellular carcinoma

AIMS

We retrospectively assessed the long-term outcomes of Yttrium-90 (90Y) transarterial radioembolization (TARE) for hepatocellular carcinoma (HCC), focusing on overall survival (OS), radiological response, and safety.

METHODS

We included patients with HCC treated with 90Y TARE at a single center between January 2012 and December 2021 with measurable lesions and a minimum of 2 years of follow-up. Only the former was analyzed for patients with multiple TARE. The primary endpoints were long-term OS, radiological response, and safety; the secondary endpoints included predictors of OS and response, with emphasis on dosimetry. The collected data included demographics, laboratory test results, liver function, and tumor staging. Radiological response was evaluated 3-6 months post-TARE using the modified RECIST (mRECIST) criteria. OS was calculated from TARE until death or censoring. Univariate logistic regression was used to identify the predictors of complete radiological response and OS. Dosimetry was analyzed to determine correlations with mRECIST response.

RESULTS

Among 142 patients (median age 66.8, cirrhotic 92.3%; M: F = 121:21), a median OS of 16.68 months was achieved, with a complete radiological response in 31% (44/142). OS was strongly correlated with radiological response (p < 0.001). Absorbed dose ≥ 234.6 Gy was associated with complete response (p = 0.017) but not with survival (p = 0.102). Rising alpha-fetoprotein levels (p = 0.017) and worsening Child-Pugh scores post-TARE (p = 0.044) were independent predictors of mortality.

CONCLUSION

A complete radiological response is crucial for long-term survival, highlighting the need for dosimetry optimization in TARE for HCC.

Evaluation of long axial field-of-view (LAFOV) PET/CT for post-treatment dosimetry in Yttrium-90 radioembolization of liver tumors: a comparative study with conventional SPECT imaging

PURPOSE

Long axial field-of-view (LAFOV) positron emission tomography/computed tomography (PET/CT) scanners enable high sensitivity and wide anatomical coverage. Therefore, they seem ideal to perform post-selective internal radiation therapy (SIRT) 90Y scans, which are needed, to confirm that the dose is delivered to the tumors and that healthy organs are spared. However, it is unclear to what extent the use of LAFOV PET is feasible and which dosimetry approaches results in accurate measurements.

METHODS

In this retrospective analysis, a total number of 32 patients was included (median age 71, IQR 14), which had hepatocellular carcinoma, cholangiocarcinoma, or liver metastases. All patients underwent SIRT, and the post-therapy scan was acquired on a single photon emission computed tomography/computed tomography (SPECT/CT) and a LAFOV Biograph Quadra PET/CT with a 20-minute acquisition time. Post-treatment dosimetry, regarding the tumor, whole-liver and lung (LMD) absorbed dose was done using an organ-wise (Simplicit90Y) and a voxel-wise approach (HERMIA Dosimetry) which used a semi-Monte Carlo algorithm. The lung shunt fraction (LSF) was also measured using the voxel-wise approach and compared to the planned.

RESULTS

The planning, post-treatment SPECT and PET (SPECTpre, SPECTpost, PETpost) median tumor doses based on the organ-wise dosimetry were 276.0 Gy (200.0-330.0 Gy), 232.0 Gy (158.5-303.5 Gy) and 267.5 Gy (182.5-370.8 Gy). In contrast, the median voxel-wise PETpost dose was significantly smaller than the planned SPECTpre (152.5 Gy (94.8-223.8 Gy); p < 0.00001). Moreover, the median tumor absorbed dose at 90% (D90) of the tumor volume was significantly higher in SPECTpost compared with PETpost (123.5 Gy; 81.5-180.0 vs. 30.5 Gy; 11.3-106.3; p < 0.00001). The PETpost measured LSF was significantly lower compared to the planned SPECTpre (0.89%; 0.4-1.3% vs. 2.3%; 1.5-3.6%; p < 0.0001). Similarly, the measured PETpost median LMD was considerably lower to the planned SPECTpre (1.2 Gy; 0.6-2.3 vs. 2.5 Gy; 1.4-4.7; p < 0.0001).

CONCLUSION

LAFOV PET enabled the direct measurement of post therapy lung dose and tumor doses that correlated well with the planned treatment doses. However, current voxel-wise-based tumor dosimetry seems to be inaccurate for LAFOV PET. In addition, dose volume histogram-based metrics also significantly underestimate the delivered dose. Therefore, improved dosimetry tools are needed for reliable voxel-wise 90Y dosimetry to leverage the sensitivity and spatial resolution of LAFOV PET scanners.

Voxel-Based Dosimetry as a Means for Treatment Personalisation in Radioembolization: A Systematic Review

INTRODUCTION

Radionuclide therapy including 90Y radioembolization is an established form of brachytherapy for treatment of malignancy including hepatocellular carcinoma. Currently, there are several methods available to estimate patient absorbed dose, including voxel-based dosimetry, that can achieve a level of personalisation in the planning and outcome assessments of radioembolization. Despite the advantages of voxel-based dosimetry, it remains a relatively new concept in radioembolization. This study evaluates if voxel-based dosimetry was associated with improved treatment efficacy in radioembolization planning.

METHODS

A systematic review was conducted by searching relevant databases (Medline Ovid, PubMed, Embase Ovid, CINAHL Complete, Cochrane Library, CENTRAL, Australian New Zealand Clinical Trials Registry, ClinicalTrials.gov, WHO International Trials Registry, Google Scholar) for literature regarding voxel-based dosimetry in radioembolization.

RESULTS

A total of 41 papers were included for this systematic review. Review of these studies revealed that voxel-based dosimetry can benefit numerous aspects of radioembolization in radionuclide therapy including predicting tumour response, toxicity and patient survival. Numerous studies also indicated that voxel-based dosimetry in radioembolization is a more accurate approach in establishing a dose-effect relationship in targeted radionuclide therapy when compared to other methods. Despite these promising findings, these studies did not investigate or comment on the accuracy of voxel-based dosimetry.

CONCLUSION

The evidence from this review highlights that voxel-based dosimetry can improve treatment efficacy in radioembolization planning. However, further studies are required to validate the accuracy and feasibility of voxel-based dosimetry in clinical practice.

In Vitro Investigation of Microcatheter Behavior During Microsphere Injection in Transarterial Radioembolization

PURPOSE

To experimentally investigate the behavior of a clinically used microcatheter during transarterial radioembolization (TARE) microsphere injection in a successively bifurcating in vitro model.

MATERIALS AND METHODS

A symmetrical phantom was developed which bifurcated 3 times into 8 outlets. A blood-mimicking fluid was pumped through the phantom using a physiological representative waveform. Holmium-165 microspheres were injected in a pulsed manner at 3 different locations using a standard microcatheter and a rigid counterpart with same dimensions as a control. Motion of the catheter was studied with a top- and side-view camera on the phantom. Microspheres were collected at each outlet and their distribution over the 8 outlets was analyzed.

RESULTS

Due to the pulsatile flow in the phantom, strengthened by the pulsatile microsphere injection, the clinical catheter showed maximum displacements of 0.87 mm within a vessel with a diameter of 3.6 mm. This motion resulted in a different microsphere distribution for the clinical catheter compared with the rigid counterpart (75.9% vs 49.4% of the microspheres went to outlet 1-4, respectively).

CONCLUSION

In this in vitro model, the motion of the clinical catheter affected distribution of microspheres. Since the pulsatile administration of microspheres resulted in increased motion of the clinical catheter, standardizing microsphere administration could be beneficial to reduce interprocedural differences in TARE.

CLINICAL IMPACT

Our study demonstrated that microsphere distribution during transarterial radioembolization (TARE) is affected by catheter motion. Furthermore, increased catheter motion was observed as a result of the injection profile. Predictive tools such as the contrast CBCT and scout dose use different injection profiles compared to therapeutic TARE injections, potentially altering catheter tip behaviour and microsphere distribution, which could compromise their predictive values. Additionally, current TARE microsphere injection guidelines provide limited details, which may lead to variability across institutes and interventional radiologists. Standardizing injection techniques could reduce catheter motion variability and may facilitate more consistent and predictable microsphere distribution patterns.

Discordance between 90Y-PET/CT(MR)-estimated activity and dose calibrator measured administered activity: an international study in SIRT patients treated with resin and glass microspheres

PURPOSE

Therapeutic administration of 90Y-loaded microspheres is routinely used for primary and secondary liver tumours. For activity-based therapeutic prescription the activity must be within 10% of the intended activity. Previous studies reported significant discrepancies between manufacturer-declared vial activities and both experimental and Monte-Carlo assessments, greater than 10%, for resin/glass 90Y-microspheres. The objective of this work was to investigate whether these discrepancies were also seen in patients.

METHODS

We analysed patient 90Y-PET reconstructions (99 glass and 15 resin microspheres) from 4 different institutions and 4 different systems. We considered tail-fitting background scaling (TFBS) and absolute scaling (ABS), for scatter correction. Residuals after therapeutic injection were measured. Eighty-one patients were imaged with PET/CT and 33 with PET/MR. The PET measured activity (APET) was assessed in the whole liver. The ratio APET/Acalibrator was calculated for each patient, where Acalibrator was the injected activity measured by the dose calibrator corrected for residual and lung shunt.

RESULTS

Quantification ratio between calibrators and PET was significantly different from 1, regardless of the scatter correction used. In glass microspheres, the mean APET/CT/Acalibrator was 0.84 ± 0.06 for TFBS and 0.90 ± 0.06 for ABS (0.66 ± 0.09 and 0.76 ± 0.07 for (APET/MR/Acalibrator)). The mean APET/CT/Acalibrator ratio for resin microspheres was 1.16 ± 0.09 for TFBS and 1.30 ± 0.12 for ABS.

CONCLUSIONS

We observed in patients similar activity discrepancies as reported for vials, with a relative difference of 44 ± 16% between glass and resin 90Y-loaded microspheres. In 90Y hepatic radioembolization, the 10% accuracy prerequisite on knowing the administered therapeutic activity is then unlikely to be met.

Structure and expression of FAPP2 protein in hepatocellular carcinoma: Its effect and molecular mechanism on HepG2 and MHCC97H in clinical treatment

Hepatocellular carcinoma (HCC) is a common and lethal malignancy of the liver. The aim of this study was to reveal the structural characteristics of FAPP2, evaluate its expression in HepG2 and MHCC97H cells, and explore its potential role and molecular mechanism in the clinical treatment of hepatocellular carcinoma. The role of FAPP2 in these two cell lines was evaluated using cell function tests, such as cell proliferation, migration, and invasion tests. The interaction between FAPP2 and other related signaling pathways was further explored by bioinformatics analysis. The structural analysis of FAPP2 shows that it has specific domains and functional sites, which are closely related to its biological function in the cell. FAPP2 expression in HepG2 cells was significantly higher than that in MHCC97H cells. Functional experiments showed that overexpression of FAPP2 promoted the proliferation and migration of HepG2 cells, but no such effect was seen in MHCC97H cells. Bioinformatics analysis revealed a potential association between FAPP2 and the PI3K/Akt signaling pathway.

Holmium-166 radioembolisation dosimetry in HCC

PURPOSE

To evaluate dosimetry, dose-response and dose-toxicity relationships for holmium-166 (166Ho) radioembolisation in patients with hepatocellular carcinoma (HCC).

METHODS

Thirty-one patients with hepatocellular carcinoma were included in the HEPAR Primary study (NCT03379844, registered on December 20th, 2017) and underwent 166Ho-microspheres radioembolisation. Linear mixed models assessed the association between tumour absorbed doses and response based on mRECIST both on tumour and patient level. Preliminary tumour absorbed dose thresholds were estimated based on predictive value. Linear regression models assessed the association between non-tumour absorbed dose and Common Terminology Criteria for Adverse Events version 4.03.

RESULTS

Median tumour absorbed dose (tumour level) was 95.5 Gy (range 44-332 Gy). Median non-tumour absorbed dose based on whole liver volume was 19 Gy (range 3 - 48 Gy) and based on target liver volume was 30 Gy (range 13 - 54 Gy). There was a significant association between non-tumour absorbed dose and toxicity. Tumours with partial response/complete response (PR/CR, responders) received a 41% higher absorbed dose than tumours with progressive disease/stable disease (PD/SD, non-responders) (95%CI: 2%-93%, p = 0.04). A predictive value of 90% for tumour response was observed at a tumour absorbed dose threshold of 155 Gy, 100% predictive value was achieved at 184.5 Gy.

CONCLUSION

This study confirms a positive relationship between tumour absorbed dose and response and between non-tumour absorbed dose and toxicity. Dose thresholds found in this study can serve as a basis for personalized dosimetry in HCC patients treated with 166Ho-microspheres.

Albi score predicts overall survival (OS) in patients with hepatocellular carcinoma (HCC) treated with selective internal radiation therapy (SIRT)

PURPOSE

We aimed to evaluate the prognostic impact of baseline clinical features and treatment procedure, including liver function measured with albumin-bilirubin (ALBI) formula and dosing methods in HCC patients treated with SIRT.

MATERIAL AND METHODS

The study includes 82 consecutive patients with liver-dominant HCC treated with SIRT (90Y glass microspheres, TheraSphereTM) between October 2014 and September 2023. Twenty-five patients were treated with standard dosimetry, while for remaining patients, multi-compartment dosimetry was performed using Simplicit90YTM software. Impact of baseline patient's characteristics including presence of portal vein thrombosis (PVT), Child-Pugh score (CP), ALBI score, bilirubin levels, tumor size and prior locoregional liver-directed or systemic treatments was assessed through multivariable Cox proportional hazard model.

RESULTS

Median follow-up after treatment was 40.0 months (15.2-67.9). At univariable analysis, ALBI score and bilirubin levels were found to be independent prognostic factors for survival after SIRT (p = 0.001, respectively); furthermore, at Cox proportional hazards analysis, HR for death of ALBI 2 versus ALBI 1 was 10.54 (95% CI, 1.42-78.19, p = 0.021), while despite not significant, HR in patients with bilirubin levels over 1.1 mg/dl was 2.67 (0.75-9.44, p = 0.118). Conversely, no significant association was found between OS and cirrhosis, tumor size and PVT.

CONCLUSION

ALBI score demonstrated to impact OS in HCC patients treated with SIRT thus going beyond a simple prediction of treatment-related toxicity. The present results are relevant for the selection of HCC patients for SIRT in a real-world clinical setting.

Utility of pre-procedural [99mTc]TcMAA SPECT/CT Multicompartment Dosimetry for Treatment Planning of 90Y Glass microspheres in patients with Hepatocellular Carcinoma: comparison of anatomic versus [99mTc]TcMAA-based Segmentation

PURPOSE

Pre-treatment [99mTc]TcMAA-based radioembolization treatment planning using multicompartment dosimetry involves the definition of the tumor and normal tissue compartments and calculation of the prescribed absorbed doses. The aim was to compare the real-world utility of anatomic and [99mTc]TcMAA-based segmentation of tumor and normal tissue compartments.

MATERIALS AND METHODS

Included patients had HCC treated by glass [90Y]yttrium microspheres, ≥ 1 tumor, ≥ 3 cm diameter and [99mTc]TcMAA SPECT/CT imaging before treatment. Segmentation was performed retrospectively using dedicated dosimetry software: (1) anatomic (diagnostic CT/MRI-based), and (2) [99mTc]TcMAA threshold-based (i.e., using an activity-isocontour threshold). CT/MRI was co-registered with [99mTc]TcMAA SPECT/CT. Logistic regression and Cox regression, respectively, were used to evaluate relationships between total perfused tumor absorbed dose (TAD) and objective response rate (ORR) and overall survival (OS). In a subset-analysis pre- and post-treatment dosimetry were compared using Bland-Altman analysis and Pearson's correlation coefficient.

RESULTS

A total of 209 patients were enrolled. Total perfused tumor and normal tissue volumes were larger when using anatomic versus [99mTc]TcMAA threshold segmentation, resulting in lower absorbed doses. mRECIST ORR was higher with increasing total perfused TAD (odds ratio per 100 Gy TAD increase was 1.22 (95% CI: 1.01-1.49; p = 0.044) for anatomic and 1.19 (95% CI: 1.04-1.37; p = 0.012) for [99mTc]TcMAA threshold segmentation. Higher total perfused TAD was associated with improved OS (hazard ratio per 100 Gy TAD increase was 0.826 (95% CI: 0.714-0.954; p = 0.009) and 0.847 (95% CI: 0.765-0.936; p = 0.001) for anatomic and [99mTc]TcMAA threshold segmentation, respectively). For pre- vs. post-treatment dosimetry comparison, the average bias for total perfused TAD was + 11.5 Gy (95% limits of agreement: -227.0 to 250.0) with a strong positive correlation (Pearson's correlation coefficient = 0.80).

CONCLUSION

Real-world data support [99mTc]TcMAA imaging to estimate absorbed doses prior to treatment of HCC with glass [90Y]yttrium microspheres. Both anatomic and [99mTc]TcMAA threshold methods were suitable for treatment planning.

TRIAL REGISTRATION NUMBER

NCT03295006.

Voxel-based dosimetry with integrated Y-90 PET/MRI and prediction of response of primary and metastatic liver tumors to radioembolization with Y-90 glass microspheres

PURPOSE

In this study, we aimed to evaluate the response of the primary and metastatic liver tumors to radioembolization with 90Y glass microspheres and investigate its correlations with dosimetric variables calculated with 90Y PET/MRI.

METHODS

In this ambispective study, 44 patients treated with 90Y glass microspheres and imaged with 90Y PET/MRI were included for analysis. Dosimetric analysis was performed for every perfused lesion using dose-volume histograms. Response was assessed by comparing pre-treatment and follow-up total lesion glycolysis (TLG) values derived from 18F-FDG PET imaging. The relationship between ΔTLG and log-transformed dosimetric variables was analyzed with linear mixed effects regression models. ROC analyses were performed to compare discriminatory power of the variables in predicting response and complete response.

RESULTS

Regression and ROC analyses demonstrated that mean tumor dose and almost all D values were statistically significant predictors of treatment response and complete treatment response. Specifically, D60, D70 and D80 values exhibited significantly higher discriminatory power for predicting treatment response compared to the mean dose (Dmean) delivered to tumor. High specificity cut-off values to predict response were determined as 160.75 Gy for Dmean, 95.50 Gy for D60, 89 Gy for D70, and 59.50 Gy for D80. Similarly, high-specificity cut-off values to predict complete response were 262.75 Gy for Dmean, 173 Gy for D70, 140.5 Gy for D80, and 100 Gy for D90.

CONCLUSION

In this study, we demonstrated that voxel-based dosimetry with post-treatment 90Y PET/MRI can predict response to treatment. D60, D70 and D80 variables also did have greater discriminatory power compared to Dmean in prediction of response. In addition, we present high-specificity cut-offs to predict response (CR + PR) and complete response (CR) for both Dmean and several D variables derived from dose-volume histograms.

Association of adverse events and quality of life in patients with unresectable hepatocellular carcinoma

PURPOSE

Hepatocellular carcinoma (HCC) is the third-leading cause of cancer-related deaths globally. Patients are often diagnosed with advanced disease, in which systemic and locoregional therapies are commonly used as first-line treatment. Such treatments can cause adverse events (AEs) that negatively affect quality of life (QoL), which is particularly undesirable where prognosis is poor. The aim of the present study was to evaluate the impact of common AEs on QoL in patients with HCC.

METHODS

Data from the SARAH randomized controlled trial (RCT) were analyzed. Given the large number of distinct AEs that occurred in the trial, AEs were grouped as in the SARAH trial and prioritized using principal component analysis (PCA). Linear mixed-effects models were then applied with age, ECOG status, and AEs as predictors of the QoL change as measured with the EORTC Core Quality of Life Questionnaire (QLQ-C30).

RESULTS

The PCA resulted in the selection of 28 AEs for inclusion in the linear mixed-effects models. Of the 28 AEs, diarrhea, decreased appetite, abdominal pain, and palmar-plantar erythrodysesthesia syndrome (hand-foot syndrome) were significant drivers of reductions in QoL as measured using the QLQ-C30 global health status scale. Diarrhea, abdominal pain, and hand-foot syndrome were also significant drivers of reduced QoL outcomes.

CONCLUSION

The present analysis showed that diarrhea, decreased appetite, abdominal pain, and palmar-plantar erythrodysesthesia were significantly associated with reduced QoL in patients with unresectable HCC. Reducing the incidence and/or severity of these AEs should therefore be a key focus when selecting the optimal treatments for these patients.

Incident cardiovascular disease risk among older Asian, Native Hawaiian and Pacific Islander liver cancer survivors

BACKGROUND

Cardiovascular disease (CVD) is a significant global health concern, particularly among Asian, Native Hawaiian, and Pacific Islander (ANHPI) communities that face unique health challenges. Liver cancer disproportionately affects ANHPI populations and has intricate associations with CVD risks due to shared pathophysiological mechanisms and metabolic disturbances. However, the specific CVD risk profile of ANHPI liver cancer patients remains poorly understood.

METHODS

Using Surveillance, Epidemiology, and End Results (SEER)-Medicare data, we identified and matched 1150 ANHPI and 2070 Non-Hispanic White (NHW) liver cancer patients diagnosed between 2000 and 2017. We used the Fine-Gray sub-distribution hazard model to estimate hazard ratios (HRs) and 95 % confidence intervals (95 % CIs) for CVD risks, including ischemic heart disease (IHD), heart failure, and stroke, among ANHPI liver cancer patients compared to NHW counterparts and among ANHPI subgroups.

RESULTS

ANHPI liver cancer patients demonstrated a lower risk of IHD compared to NHW counterparts (HR, 0.65, 95 % CI, 0.50, 0.86), aligning with broader trends. Subgroup analysis revealed notable heterogeneity within ANHPI populations, with Southeast Asian (HR, 0.65, 95 % CI, 0.42, 1.00) and Chinese patients (HR, 0.53, 95 % CI, 0.33-0.83) exhibiting lower IHD risks compared to their NHW counterparts. However, Native Hawaiian and Pacific Islander liver cancer patients showed elevated risks of heart failure (HR, 3.16, 95 % CI, 1.35-7.39) and IHD (HR, 5.64, 95 % CI, 2.19-14.53) compared to their Chinese counterparts.

CONCLUSION

Our study highlights the complexity of CVD risks among ANHPI liver cancer patients. Addressing these disparities is crucial for improving cardiovascular outcomes and reducing the burden of CVD among ANHPI liver cancer patients.

Adverse reactions to therapeutic radiopharmaceuticals

Radiopharmaceuticals are drugs used in treatment or diagnosis that contain a radioactive part, usually a pharmaceutical part in their structure. Adverse drug reactions are harmful and unexpected responses that occur when administered at normal doses. Although radiopharmaceuticals are regarded as safe medical products, adverse reactions should not be ignored. More serious adverse reactions such as myelosuppression, pleural effusion, and death may develop in therapeutic radiopharmaceuticals due to their use at higher doses than those used in diagnosis. Therefore, monitoring adverse reactions and reporting them to health authorities is important. This review aims to provide information about adverse reactions that may be related to radiopharmaceuticals used in treatment.

Radiotherapy as a metastasis directed therapy for liver oligometastases - comparative analysis between CT-guided interstitial HDR brachytherapy and two SBRT modalities performed on double-layer and single layer LINACs

Introduction

Surgical resection is gold standard for treatment of liver metastasis, locally ablative techniques including computer tomography (CT)-guided interstitial high-dose-rate (HDR) brachytherapy (CT-BRT) and stereotactic body radiotherapy (SBRT) have gained prominence as alternatives, offering comparable outcomes in selected patients. We aim to compare CT-BRT and SBRT - based on dosimetric analysis.

Material and methods

Patients who underwent CT-BRT for oligometastatic, ≤4cm liver metastases between 2018 and 2024 were eligible. SBRT plans for Halcyon (SBRTh) and TrueBeam (SBRTtb) were prepared virtually. In the CT-BRT group CTV was equal to PTV, for SBRTh and SBRTtb planning, a 5 mm margin was applied to CTV to create PTV. Dose calculation was carried out with the TG-43 algorithm for CT-BRT and Anisotropic Analytical Algorithm for SBRTh and SBRTtb group. Descriptive statistics were used to compare the data. The Wilcoxon pairwise order test was utilized to compare dependent groups.

Results

CT-BRT resulted in a more favorable dose distribution within PTVs for Dmean, D50, and D90, while SBRT showed better results for D98 and V27.5Gy. No significant differences were observed for V25Gy between CT-BRT and SBRTtb, but SBRTh favored over CT-BRT. For OARs, CT-BRT plans showed better values for V5, V10, and V11.6Gy in the uninvolved liver volume. There were no significant differences in dose distribution for the duodenum, bowel, and heart. SBRT modalities performed better in the kidney. CT-BRT had improved dose distribution in the esophagus, great vessels, ribs, skin, spinal cord, and stomach compared to SBRT.

Conclusions

CT-BRT could be a viable alternative to SBRT for certain patients with liver malignancies.

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.

A 78-Year-Old Man With Shortness of Breath After Radioembolization of the Liver

CASE PRESENTATION

A 78-year-old man with a history of GI stromal tumor (GIST) in the stomach with metastasis to the liver presented with progressive shortness of breath, dry cough, and subjective fever that started 1 week after radioembolization of liver metastatic lesions. His initial diagnosis of GIST was 10 years before, for which he underwent surgical resection; however, more recently he was noted to have hepatic lesions biopsy-proven to be metastatic GIST lesions. He stated that he did not have any respiratory symptoms before the radioembolization procedure and denied having a history of pulmonary disease. His medical history was otherwise notable for coronary artery disease post coronary artery bypass graft in 2002, heart failure with reduced ejection fraction, and atrioventricular block after pacemaker placement. After the diagnosis of liver metastasis, he began treatment with imatinib 6 months earlier and consequently received radioembolization with yttrium-90 (Y-90) microspheres.

New frontiers in radioembolization

Radioembolization is a locoregional transarterial therapy that combines radionuclide and micron-sized beads to deliver radiation internally to the target tumors based on the arterial blood flow. While initially developed as a palliative treatment option, radioembolization is now used for curative intent treatment, neoadjuvant therapy, and method to downstage or bridge for liver transplant. Radioembolization has become increasingly utilized and is an important therapeutic option for the management of hepatocellular carcinoma and liver metastasis. This article provides an overview of the techniques, challenges, and novel developments in radioembolization, including new dosimetry techniques, radionuclides, and new target tumors.

Navigating the landscape of theranostics in nuclear medicine: current practice and future prospects

Theranostics refers to the combination of diagnostic biomarkers with therapeutic agents that share a specific target expressed by diseased cells and tissues. Nuclear medicine is an exciting component explored for its applicability in theranostic concepts in clinical and research investigations. Nuclear theranostics is based on the employment of radioactive compounds delivering ionizing radiation to diagnose and manage certain diseases employing binding with specifically expressed targets. In the realm of personalized medicine, nuclear theranostics stands as a beacon of potential, potentially revolutionizing disease management. Studies exploring the theranostic profile of radioactive compounds have been presented in this review along with a detailed explanation of radioactive compounds and their theranostic applicability in several diseases. It furnishes insights into their applicability across diverse diseases, elucidating the intricate interplay between these compounds and disease pathologies. Light is shed on the important milestones of nuclear theranostics beginning with radioiodine therapy in thyroid carcinomas, MIBG labelled with iodine in neuroblastoma, and several others. Our perspectives have been put forth regarding the most important theranostic agents along with emerging trends and prospects.

First-Strike Rapid Predictive Dosimetry and Dose Response for 177Lu-PSMA Therapy in Metastatic Castration-Resistant Prostate Cancer

We devised and clinically validated a schema of rapid personalized predictive dosimetry for 177Lu-PSMA-I&T in metastatic castration-resistant prostate cancer. It supersedes traditional empiric prescription by providing clinically meaningful predicted absorbed doses for first-strike optimization. Methods: Prostate-specific membrane antigen PET was conceptualized as a simulation study that captures the complex dosimetric interplay between tumor, marrow, and kidneys at a single time point. Radiation principles of fractionation, heterogeneity, normal-organ constraints (marrow, kidney), absorbed dose, and dose rate were introduced. We created a predictive calculator in the form of a free, open-source, and user-friendly spreadsheet that can be completed within minutes. Our schema achieves speed and accuracy by sampling tissue radioconcentrations (kBq/cm3) to be analyzed in conjunction with clinical input from the user that reflect dosimetric preconditions. The marrow-absorbed dose constraint was 0.217 Gy (dose rate, ≤0.0147 Gy/h) per fraction with an interfraction interval of at least 6 wk. Results: Our first 10 patients were analyzed. The first-strike mean tumor-absorbed dose threshold for any prostate-specific antigen (PSA) response was more than 10 Gy (dose rate, >0.1 Gy/h). The metastasis with the lowest first-strike tumor-absorbed dose correlated the best with the percentage decrease of PSA; its threshold to achieve hypothetical zero PSA was 20 Gy or more. Each patient's PSA doubling time can be used to personalize their unique absorbed dose-response threshold. The predicted mean first-strike prescription constrained by marrow-absorbed dose rate per fraction was 11.0 ± 4.0 GBq. Highly favorable conditions (tumor sink effect) were dosimetrically expressed as the combination of tumor-to-normal-organ ratios of more than 150 for marrow and more than 4 for kidney. Our schema obviates the traditional role of the SUV as a predictive parameter. Conclusion: Our rapid schema is feasible to implement in any busy real-world theranostics unit and exceeds today's best practice standards. Our dosimetric thresholds and predictive parameters can radiobiologically rationalize each patient's first-strike prescription down to a single becquerel. Favorable tumor-to-normal-organ ratios can be prospectively exploited by predictive dosimetry to optimize the first-strike prescription. The scientific framework of our schema may be applied to other systemic radionuclide therapies.

Feasibility of Liver Transplantation after 90 Y Radioembolization: Lessons from a Radiation Protection Incident

ABSTRACT

Radioembolization using 90 Y is a growing procedure in nuclear medicine for treating hepatocellular carcinoma. Current guidelines suggest postponing liver transplantation or surgical resection for a period of 14 to 30 d after radioembolization to minimize surgeons' exposure to ionizing radiation. In light of a radiation protection incident, we reevaluated the minimum delay required between radioembolization and subsequent liver transplantation. A patient with a hepatocellular carcinoma underwent a liver transplantation 44 h after undergoing radioembolization using 90 Y (860 MBq SIR-Spheres). No specific radioprotection measures were followed during surgery and pathological analysis. We subsequently (1) evaluated the healthcare professionals' exposure to ionizing radiation by conducting dose rate measurements from removed liver tissue and (2) extrapolated the recommended interval to be observed between radioembolization and surgery/transplantation to ensure compliance with the radiation dose limits for worker safety. The surgeons involved in the transplantation procedure experienced the highest radiation exposure, with whole-body doses of 2.4 mSv and extremity doses of 24 mSv. The recommended delay between radioembolization and liver transplantation was 8 d when using SIR-Spheres and 15 d when injecting TheraSphere. This delay can be reduced further when considering the specific 90 Y activity administered during radioembolization. This dosimetric study suggests the feasibility of shortening the delay for liver transplantation/surgery after radioembolization from the 8th or 15th day after using SIR-Spheres or TheraSphere, respectively. This delay can be decreased further when adjusted to the administrated activity while upholding radiation protection standards for healthcare professionals.

Conversion Therapy to Transplant or Surgical Resection in Patients with Unresectable Hepatocellular Carcinoma Treated with Boosted Dose of Yttrium-90 Radiation Segmentectomy

BACKGROUND/OBJECTIVES

The aim of this study was to assess the efficacy of boosted dose yttrium-90 radioembolization (TARE) as a modality for conversion therapy to transplant or surgical resection in patients with unresectable hepatocellular carcinoma (HCC).

METHODS

In this single-center retrospective study, all patients with a diagnosis of HCC who were treated with boosted dose TARE (>190 Gy) between January 2013 and December 2023 were reviewed. Treatment response and decrease in tumor size were assessed with the RECIST v1.1 and mRECIST criteria. Milan and University of California, San Francisco (UCSF), criteria were used to determine transplant eligibility, and Barcelona Clinic Liver Cancer (BCLC) surgical resection recommendations were used to evaluate tumor resectability.

RESULTS

Thirty-eight patients with primary HCC who were treated with boosted dose TARE were retrospectively analyzed. The majority of the patients were Child-Pugh A (n = 35; 92.1%), BCLC C (n = 17; 44.7%), and ECOG performance status 0 (n = 25; 65.8%). The mean sum of the target lesions was 6.0 cm (standard deviation; SD = 4.0). The objective response rate (ORR) was 31.6% by RECIST and 84.2% by mRECIST. The disease control rate (DCR) was 94.7% by both RECIST and mRECIST. Among patients outside of Milan or UCSF, 13/25 (52.0%, Milan) and 9/19 (47.4%, UCSF) patients were successfully converted to within transplant criteria. Of patients who were initially unresectable, conversion was successful in 7/26 (26.9%) patients.

CONCLUSIONS

This study provides further real-world data demonstrating that boosted-dose TARE is an effective modality for conversion of patients with unresectable HCC to transplant or resection.

Dose-Response Relationship in Patients with Liver Metastases from Neuroendocrine Neoplasms Undergoing Radioembolization with 90Y Glass Microspheres

The benefit of multicompartment dosimetry in the radioembolization of neuroendocrine neoplasms is not firmly established. We retrospectively assessed its potential with patient outcome. Methods: Forty-three patients were eligible. The association of mean absorbed dose (MAD) for tumors and treatment response was tested per lesion with a receiver operating characteristic curve analysis, and the association of MAD with progression-free survival (PFS) and overall survival was tested per patient using uni- and multivariate Cox regression analyses. Results: The area under the curve for treatment response based on MAD was 0.79 (cutoff, 196.6 Gy; P < 0.0001). For global PFS, grade (grade 2 vs. 1: hazard ratio [HR], 2.51; P = 0.042; grade 3 vs. 1: HR, 62.44; P < 0.001), tumor origin (HR, 6.58; P < 0.001), and MAD (HR, 0.998; P = 0.003) were significant. For overall survival, no prognostic parameters were significant. Conclusion: In line with prior publications, a MAD of more than 200 Gy seemed to favor treatment response. MAD was also associated with PFS and may be of interest for radioembolization planning for neuroendocrine neoplasm patients.

Establishing Updated Safety Standards for Independent 99mTc-MAA SPECT/CT Treatment Planning in Radioembolization

PURPOSE

Significant improvements within radioembolization imaging and dosimetry permit the development of an accurate and personalized pretreatment plan using technetium 99m-labeled macroaggregated albumin (99mTc-MAA) and single-photon emission computed tomography (SPECT) combined with anatomical CT (SPECT/CT). Despite these potential advantages, the clinical transition to pretreatment protocols with SPECT/CT is hindered by their unknown safety constraints. This study aimed to address this issue by establishing novel dose limits for 99mTc-MAA SPECT/CT to enable quantitative pretreatment planning.

METHODS AND MATERIALS

Stratification criteria to determine images most viable for dosimetry analysis were created from a cohort of 85 patients. SPECT/CT, cone beam CT, and activity calculations derived from the local deposition method were used to create an accurate pretreatment protocol. Planar and SPECT/CT images were compared using linear regression and modified Bland-Altman analyses to convert accepted planar dose limits to SPECT/CT. To validate these new dose limits, activity calculations based on SPECT/CT were compared with those calculated with the body surface area and planar methods for three treatment plans.

RESULTS

A total of 38 of 85 patients were deemed viable for dosimetry analysis. SPECT yielded greater lung shunt fractions (LSFs) than planar imaging when LSFs were <4.89%, whereas SPECT yielded lower LSFs than planar imaging when LSFs were >4.89%. Planar to SPECT/CT dose conversions were 0.76×, 0.70×, and 0.55× for the whole liver, normal liver, and lungs, respectively. Patients with SPECT LSFs ≤4.89% were safely treated with the direct application of planar lung dose limits. Activity calculations with the newly established SPECT/CT dose limits were greater than those of the body surface area method by a median range of 33.1% to 61.9% and were lower than planar-based activity calculations by a median range of 12.5% to 13.7% for the whole liver and by 29.4% to 32.2% for the normal liver.

CONCLUSIONS

This study demonstrated a safe method for translating dose limits from 99mTc-MAA planar imaging to SPECT/CT. A robust pretreatment protocol was further developed guided by the current knowledge in the field. Established SPECT/CT dose limits safely treated 97.5% of patients and permitted the application of independent pretreatment planning with 99mTc-MAA SPECT/CT.

Use of dose-volume histograms for metabolic response prediction in hepatocellular carcinoma patients undergoing transarterial radioembolization with Y-90 resin microspheres

INTRODUCTION

Voxel-based dosimetry offers improved outcomes in the treatment of hepatocellular carcinoma (HCC) with transarterial radioembolization (TARE) using glass microspheres. However, the adaptation of voxel-based dosimetry to resin-based microspheres has been poorly studied, and the prognostic relevance of heterogeneous dose distribution remains unclear. This study aims to explore the use of dose-volume histograms for resin microspheres and to determine thresholds for objective metabolic response in HCC patients treated with resin-based TARE.

METHODS

We retrospectively reviewed HCC patients who underwent TARE with Y-90-loaded resin microspheres in our institution between January 2021 and December 2022. Voxel-based dosimetry was performed on post-treatment Y-90 PET/CT images to extract parameters including mean dose absorbed by the tumor (mTD), the percentage of the targeted tumor volume (pTV), and the minimum doses absorbed by consecutive percentages within the tumor volume (D10, D25, D50, D75, D90). Assessment of metabolic response was done according to PERCIST criteria with F-18 FDG PET/CT imaging at 8-12 weeks after the treatment.

RESULTS

This study included 35 lesions targeted with 22 TARE sessions in 19 patients (15 males, 4 females, mean age 60 ± 13 years). Objective metabolic response was achieved in 43% of the lesions (n = 15). Responsive lesions had significantly higher mTD, pTV, and D25-D90 values (all p < 0.05). Optimal cut-off values for mTD, pTV, and D50 were 94.6 Gy (sensitivity 73%, specificity 70%, AUC 0.72), 94% (sensitivity 73%, specificity 55%, AUC 0.64), and 91 Gy (sensitivity 80%, specificity 80%, AUC 0.80), respectively.

CONCLUSION

Parameters derived from dose-volume histograms could offer valuable insights for predicting objective metabolic response in HCC patients treated with resin-based TARE. If verified with larger prospective cohorts, these parameters could enhance the precision of dose distribution and potentially optimize treatment outcomes.

Hepatic Radioembolization: A Multistep Theragnostic Procedure

This article provides a thorough overview of the practice and multistep approach of hepatic radioembolization. The current literature on hepatic radioembolization in primary or metastatic liver tumors as well as future perspectives are discussed.

The Impact of Local Control on Overall Survival after Y-90 Selective Internal Radiotherapy of Liver Metastases in Oligometastatic Cancer: A Retrospective Analysis

Y-90 Selective Internal Radiotherapy (SIRT) is an ablative therapy used for inoperable liver metastasis. The purpose of this investigation was to examine the impact of local control after SIRT on overall survival (OS) in oligometastatic patients. A retrospective, single-institution study identified oligometastatic patients with ≤5 non-intracranial metastases receiving unilateral or bilateral lobar Y-90 SIRT from 2009 to 2021. The primary endpoint was OS defined from Y-90 SIRT completion to the date of death or last follow-up. Local failure was classified as a progressive disease at the target lesion(s) by RECIST v1.1 criteria starting at 3 months after SIRT. With a median follow-up of 15.7 months, 33 patients were identified who had a total of 79 oligometastatic lesions treated with SIRT, with the majority histology of colorectal adenocarcinoma (n = 22). In total, 94% of patients completed the Y-90 lobectomy. Of the 79 individual lesions treated, 22 (27.8%) failed. Thirteen patients received salvage liver-directed therapy following intrahepatic failure; ten received repeat SIRT. Median OS (mOS) was 20.1 months, and 12-month OS was 68.2%. Intralesional failure was associated with worse 1 y OS (52.3% vs. 86.2%, p = 0.004). These results suggest that intralesional failure following Y-90 may be associated with inferior OS, emphasizing the importance of disease control in low-metastatic-burden patients.

DosePatch: physics-inspired cropping layout for patch-based Monte Carlo simulations to provide fast and accurate internal dosimetry

BACKGROUND

Dosimetry-based personalized therapy was shown to have clinical benefits e.g. in liver selective internal radiation therapy (SIRT). Yet, there is no consensus about its introduction into clinical practice, mainly as Monte Carlo simulations (gold standard for dosimetry) involve massive computation time. We addressed the problem of computation time and tested a patch-based approach for Monte Carlo simulations for internal dosimetry to improve parallelization. We introduce a physics-inspired cropping layout for patch-based MC dosimetry, and compare it to cropping layouts of the literature as well as dosimetry using organ-S-values, and dose kernels, taking whole-body Monte Carlo simulations as ground truth. This was evaluated in five patients receiving Yttrium-90 liver SIRT.

RESULTS

The patch-based Monte Carlo approach yielded the closest results to the ground truth, making it a valid alternative to the conventional approach. Our physics-inspired cropping layout and mosaicking scheme yielded a voxel-wise error of < 2% compared to whole-body Monte Carlo in soft tissue, while requiring only ≈  10% of the time.

CONCLUSIONS

This work demonstrates the feasibility and accuracy of physics-inspired cropping layouts for patch-based Monte Carlo simulations.

Safety and efficacy of Holmium-166 selective internal radiotherapy of primary and secondary liver cancer confirmed by real-world data

Purpose

Holmium-166 has emerged as a promising option for selective internal radiotherapy (SIRT) for hepatic malignancies, but data on routine clinical use are lacking. The purpose of this study was to describe the safety and effectiveness of Holmium-166 SIRT in real-world practice through retrospective analysis of a multicenter registry.

Methods

Retrospective analysis was conducted on Holmium-166 SIRT procedures performed between July 15, 2019, and July 15, 2021, across seven European centers. Treatment planning, treatment realization and post-treatment follow-up were conducted according to routine local practice. Safety and effectiveness data were extracted from the patients’ health records. Primary endpoint analysis was assessed for the entire study population with separate analysis for subgroups with hepatocellular carcinoma, metastatic colorectal cancer and intrahepatic cholangiocarcinoma.

Results

A total of 167 SIRT procedures in 146 patients (mean age 66 ± 11 years, 68% male) were retrospectively evaluated. Most common tumor entities were hepatocellular carcinoma (n=55), metastatic colorectal cancer (n=35), intrahepatic cholangiocarcinoma (n=19) and metastatic neuroendocrine tumors (n=10). Nine adverse events grade ≥ 3 according to Common Terminology Criteria for Adverse Events were recorded, including one fatal case of radioembolization-induced liver disease. Response rates and median overall survival for the above mentioned subgroups were comparable to results from previous Holmium-166 trials as well as to results from Yttrium-90 registries.

Conclusion

This study confirms that the safety and effectiveness of Holmium-166 SIRT derived from prospective trials also applies in routine clinical practice, reinforcing its potential as a viable treatment option for primary and secondary liver cancer.

Safety and efficacy of Holmium-166 selective internal radiotherapy of primary and secondary liver cancer confirmed by real-world data

PURPOSE

Holmium-166 has emerged as a promising option for selective internal radiotherapy (SIRT) for hepatic malignancies, but data on routine clinical use are lacking. The purpose of this study was to describe the safety and effectiveness of Holmium-166 SIRT in real-world practice through retrospective analysis of a multicenter registry.

METHODS

Retrospective analysis was conducted on Holmium-166 SIRT procedures performed between July 15, 2019, and July 15, 2021, across seven European centers. Treatment planning, treatment realization and post-treatment follow-up were conducted according to routine local practice. Safety and effectiveness data were extracted from the patients' health records. Primary endpoint analysis was assessed for the entire study population with separate analysis for subgroups with hepatocellular carcinoma, metastatic colorectal cancer and intrahepatic cholangiocarcinoma.

RESULTS

A total of 167 SIRT procedures in 146 patients (mean age 66 ± 11 years, 68% male) were retrospectively evaluated. Most common tumor entities were hepatocellular carcinoma (n=55), metastatic colorectal cancer (n=35), intrahepatic cholangiocarcinoma (n=19) and metastatic neuroendocrine tumors (n=10). Nine adverse events grade ≥ 3 according to Common Terminology Criteria for Adverse Events were recorded, including one fatal case of radioembolization-induced liver disease. Response rates and median overall survival for the above mentioned subgroups were comparable to results from previous Holmium-166 trials as well as to results from Yttrium-90 registries.

CONCLUSION

This study confirms that the safety and effectiveness of Holmium-166 SIRT derived from prospective trials also applies in routine clinical practice, reinforcing its potential as a viable treatment option for primary and secondary liver cancer.

Cost-Effectiveness and Budget Impact Analyses of Selective Internal Radiation Therapy versus Atezolizumab Plus Bevacizumab from a German Statutory Health Insurance Perspective

Purpose

To compare personalized dosimetry with yttrium-90 (90Y)-loaded glass microspheres (SIRT) vs atezolizumab and bevacizumab (A+B) in hepatocellular carcinoma (HCC) treatment in terms of cost-effectiveness and budget impact from a German statutory health insurance (SHI) perspective.

Patients and Methods

Cost-effectiveness analysis (CEA) and budget impact analysis (BIA) models were developed in MS Excel. The available key studies (IMbrave150 and DOSISPHERE-01) suggest that both strategies are comparable in terms of progression-free survival and overall survival in HCC, but a difference in severe adverse events (SAE) in favor of SIRT was observed. Accordingly, the CEA model investigates the endpoints "cost per SAE avoided" and "cost per quality-adjusted life year (QALY) gained", whereas the BIA simulates the impact of a stepwise re-allocation of current market share to the option which emerges as more cost-effective from the CEA.

Results

The model suite estimated a mean annual total per-patient costs of € 29,984 for SIRT, compared to € 75,725 for A+B. SIRT was associated with a lower number of SAE and a higher number of QALYs compared to A+B. Switching additionally 25% of the eligible patients (≈500) from systemic therapy to SIRT could generate annual savings of approximately € 22.6 million Euros to the SHI.

Conclusion

SIRT was identified as dominant treatment strategy. SIRT use not only saves SHI expenditure compared to systemic immunotherapy but also yields extra QALYs. This positions SIRT as the dominant and more cost-effective treatment strategy for patients with HCC. The savings to the SHI system, derived from the BIA conducted, become increasingly significant with rising adoption rates of SIRT.

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.