Calculation of tumour and normal tissue biological effective dose in 90 Y liver radioembolization with different dosimetric methods

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.

Comparison of absorbed doses to the tumoral and non-tumoral liver in HCC patients undergoing 99mTc-MAA and 90Y-microspheres radioembolization

PURPOSE

This study aimed to determine the absorbed doses in the tumoral-liver and non-tumoral liver of hepatocellular carcinoma (HCC) patients undergoing radioembolization with Yttrium-90 (90Y) resin microspheres, and compared with those derived from 99mTc-MAA using the partition model.

METHODS

A total of 42 HCC patients (28 males and 14 females, mean age 65 ± 11.51 years) who received 45 treatment sessions with 90Y-microspheres between 2016 and 2021 were included. Pre-treatment 99mTc-MAA and post-treatment 90Y-bremsstrahlung SPECT/CT were acquired for each patient. Semi-automated segmentation of regions of interest (ROIs) was performed using MIM Encore software to determine the tumor-liver ratio (TLR) encompassing the liver volume, tumoral-liver, and lungs, and verified by both nuclear medicine physician and interventional radiologist. A partition dosimetry model was used to estimate the administered activity of 90Y-microspheres and the absorbed doses to the tumoral-liver and non-tumoral liver. The student's paired t test and Bland-Altman plot were used for the statistical analysis.

RESULTS

The mean TLR values obtained from 99mTc-MAA SPECT/CT and 90Y-bremsstrahlung SPECT/CT were 4.78 ± 3.51 and 2.73 ± 1.18, respectively. The mean planning administered activity of 90Y-microspheres based on 99mTc-MAA SPECT/CT was 1.56 ± 0.80 GBq, while the implanted administered activity was 2.53 ± 1.23 GBq (p value < 0.001). The mean absorbed doses in the tumoral-liver estimated from 99mTc-MAA and 90Y-bremsstrahlung SPECT/CT were 127.44 ± 4.36 Gy and 135.98 ± 6.30 Gy, respectively. The corresponding mean absorbed doses in the non-tumoral liver were 34.61 ± 13.93 Gy and 55.04 ± 16.36 Gy.

CONCLUSION

This study provides evidence that the administered activity of 90Y-microspheres, as estimated from 90Y-bremsstrahlung SPECT/CT, was significantly higher than that estimated from 99mTc-MAA SPECT/CT resulted in increased absorbed doses in both the tumoral-liver and non-tumoral liver. However, 99mTc-MAA SPECT/CT remains a valuable planning tool for predicting the distribution of 90Y-microspheres in liver cancer treatment.

Simplification of dosimetry in 90Y-radioembolization therapy by dual planar images

AIM

The purpose was to provide a practical and effective method for performing reliable ⁹⁰Y dosimetry based on ^99mTc-MAA and SPEC/CT. The impact of scatter correction (SC) and attenuation correction (AC) on the injected ⁹⁰Y activity, lung shunt fraction (LSF) and the delivered dose to lung and liver compartments was investigated within the scope of the study.

MATERIAL AND METHODS

Eighteen eligible patients (F: 3, M: 15) were subjected to ⁹⁰Y therapy. ^99mTc-MAA (111-222 MBq) was injected into the targeted liver, followed by whole-body scan (WBS) with peak-window at 140 keV (15% width) and one down-scatter window. SPECT/CT scan was subsequently acquired encompassing lung and liver regions. The LSFs were fashioned from standard WBS LSFwb (St), scatter corrected WBS LSFwb (Sc), only scatter corrected SPECT LSFspect (NoAC-SC) and SPECT/CT with attenuation and scatter correction LSFspect (AC-SC). The absorbed doses that would be delivered to tumor and injected healthy liver were estimated using different calculation modes involving AC-SC (SPECT/CT), NoAC-SC (SPECT), NoAC-NoSC+LSFwb (SC), AC-SC + LSFwb (St), and NoAC-NoSC+LSFwb (St).

RESULTS

The average deviations (range) in LSF values between standard LSFwb (St) and those from SPECT/CT (AC-SC), SPECT (NoAC-SC), and LSFwb (SC) were - 50% (- 29/- 71), - 32% (- 8/- 67), and - 45% (- 13/80), respectively. The suggested ⁹⁰Y activity (GBq/Gy) was decreased within a range of 2-11%, 1-9%, and 2-7% by using LSFspect (AC-SC), LSFspect (NoAC-SC), and LSFwb (SC), respectively. Overall, two-sample t-test yielded no statistically significant difference (p < 0.05) in the absorbed doses to tumor and injected healthy liver between AC-SC (SPECT) and the rest of approaches with/and without AC and SC. However, a statistically significant difference (p < 0.05) was demonstrated in the lung shunt fractions and lung doses due to AC and SC. The LSFs from scatter corrected planar images LSFwb (SC) exhibited well agreement (R₂ = 0.92) with SPECT/CT (AC-SC) and there was no statistically significant difference (P_value > 0.05) between both methods.

CONCLUSION

It was deduced that SPECT/CT with attenuation and scatter correction plays a crucial role in the measurements of lung shunt fraction and dose as well as the total number of ⁹⁰Y treatments. However, the absorbed dose to tumors and injected healthy liver was minimally affected by AC and SC. Besides, a good agreement was observed between LSF datasets from SPECT/CT versus scatter corrected WBS that can be alternatively and effectively used in ⁹⁰Y dosimetry.

Clinical consensus statement: Selective internal radiation therapy with yttrium 90 resin microspheres for hepatocellular carcinoma in Asia

BACKGROUND

Hepatocellular carcinoma (HCC) is subject to different management approaches and guidelines according to Eastern and Western therapeutic algorithms. Use of selective internal radiation therapy (SIRT) with resin yttrium 90 microspheres for HCC has increased in Asia in recent years, without clearly defined indications for its optimal application. The objective of this systematic review and expert consensus statement is to provide guidance and perspectives on the use of SIRT among patients with HCC in Asia.

MATERIALS AND METHODS

A systematic literature review identified current publications on HCC management and SIRT recommendations. A group of 10 experts, representing stakeholder specialties and countries, convened between August 2020 and March 2021 and implemented a modified Delphi consensus approach to develop guidelines and indications for use of SIRT for HCC in Asia. Final recommendations were organized and adjudicated based on the level of evidence and strength of recommendation, per approaches outlined by the American College of Cardiology/American Heart Association and Oxford Centre for Evidence-Based Medicine.

RESULTS

The experts acknowledged a general lack of evidence relating to use of SIRT in Asia and identified as an unmet need the lack of phase 3 randomized trials comparing clinical outcomes and survival following SIRT versus other therapies for HCC. Through an iterative process, the expert group explored areas of clinical relevance and generated 31 guidance statements and a patient management algorithm that achieved consensus.

CONCLUSION

These recommendations aim to support clinicians in their decision-making and to help them identify and treat patients with HCC using SIRT in Asia. The recommendations also highlight areas in which further clinical trials are needed to define the role of SIRT in management of HCC among Asian populations.

Safety and initial efficacy of ablative radioembolization for the treatment of unresectable intrahepatic cholangiocarcinoma

PURPOSE

To investigate safety, response, and survival after ablative glass microsphere ⁹⁰Y radioembolization for unresectable intrahepatic cholangiocarcinoma.

MATERIALS AND METHODS

A retrospective review of 37 radioembolizations in 28 patients treated with single compartment dose of ≥190 Gy encompassing >75% of the largest tumor was performed. Tumors were assessed for stage, morphology, and arterial supply. Response per Modified Response Evaluation Criteria in Solid Tumors (mRECIST), freedom from progression (FFP), progression-free survival (PFS), overall survival (OS), biochemical hepatic function, performance status, and adverse events were investigated.

RESULTS

The median highest dose per patient was 256.8 Gy (195.7-807.8). Objective response at 3 months was 94.1% (complete 44.1% and partial 50%). Median OS was not reached and the 30-month OS rate was 59%, with a median follow-up of 13.4 months (5.4-39.4). FFP in the radiated field and overall FFP at 30 months were 67% and 40%, respectively. Favorable arterial supply was associated with improved OS (p = 0.018). Unfavorable arterial supply was associated with worse OS [HR 5.7 (95% CI 1.1-28.9, p = 0.034)], and PFS [HR 5.9 (95% CI 1.9-18.4, p = 0.002)]. Patients with mass-forming tumors had a survival benefit (p = 0.002). Laboratory values and performance status did not significantly change 3 months after radioembolization. Grade 3 and 4 adverse events occurred in 2 (7.1%) patients.

CONCLUSIONS

Radioembolization of unresectable intrahepatic cholangiocarcinoma with ablative intent has a high response rate, promising survival, and is well tolerated.

3D image-based dosimetry for Yttrium-90 radioembolization of hepatocellular carcinoma: Impact of imaging method on absorbed dose estimates

BACKGROUND

To improve therapy outcome of Yttrium-90 selective internal radiation therapy (⁹⁰Y SIRT), patient-specific post-therapeutic dosimetry is required. For this purpose, various dosimetric approaches based on different available imaging data have been reported. The aim of this work was to compare post-therapeutic 3D absorbed dose images using Technetium-99m (^99mTc) MAA SPECT/CT, Yttrium-90 (⁹⁰Y) bremsstrahlung (BRS) SPECT/CT, and ⁹⁰Y PET/CT.

METHODS

Ten SIRTs of nine patients with unresectable hepatocellular carcinoma (HCC) were investigated. The ^99mTc SPECT/CT data, obtained from ^99mTc-MAA-based treatment simulation prior to ⁹⁰Y SIRT, were scaled with the administered ⁹⁰Y therapy activity. 3D absorbed dose images were generated by dose kernel convolution with scaled ^99mTc/⁹⁰Y SPECT/CT, ⁹⁰Y BRS SPECT/CT, and ⁹⁰Y PET/CT data of each patient. Absorbed dose estimates in tumor and healthy liver tissue obtained using the two SPECT/CT methods were compared against ⁹⁰Y PET/CT.

RESULTS

The percentage deviation of tumor absorbed dose estimates from ⁹⁰Y PET/CT values was on average -2 ± 18% for scaled ^99mTc/⁹⁰Y SPECT/CT, whereas estimates from ⁹⁰Y BRS SPECT/CT differed on average by -50 ± 13%. For healthy liver absorbed dose estimates, all three imaging methods revealed comparable values.

CONCLUSION

The quantification capabilities of the imaging data influence ⁹⁰Y SIRT tumor dosimetry, while healthy liver absorbed dose values were comparable for all investigated imaging data. When no ⁹⁰Y PET/CT image data are available, the proposed scaled ^99mTc/⁹⁰Y SPECT/CT dosimetry method was found to be more appropriate for HCC tumor dosimetry than ⁹⁰Y BRS SPECT/CT based dosimetry.

Timeline of Translational Formulation Technologies for Cancer Therapy: Successes, Failures, and Lessons Learned Therefrom

Over the past few decades, the field of cancer therapy has seen a significant change in the way in which formulations are designed and developed, resulting in more efficient products that allow us to ultimately achieve improved drug bioavailability, efficacy, and safety. However, although many formulations have entered the market, many others have fallen by the wayside leaving the scientific community with several lessons to learn. The successes (and failures) achieved with formulations that have been approved in Europe and/or by the FDA for the three major types of cancer therapy (peptide-based therapy, chemotherapy, and radiotherapy) are reviewed herein, covering the period from the approval of the first prolonged-release system for hormonal therapy to the appearance of the first biodegradable microspheres intended for chemoembolization in 2020. In addition, those products that have entered phase III clinical trials that have been active over the last five years are summarized in order to outline future research trends and possibilities that lie ahead to develop clinically translatable formulations for cancer treatment.

PET-CT post therapy dosimetry in radioembolization with resin 90Y microspheres: Comparison with pre-treatment SPECT-CT 99mTc-MAA results

Resin microspheres radioembolization is an effective treatment for liver tumors when the surgical option is not feasible. Doses delivered to tumor and normal liver can be assess in the pre-therapy phase by means of a ^99mTc-MAA SPECT-CT simulation and after the treatment with ⁹⁰Y PET-CT acquisition. The optimal therapeutic ⁹⁰Y activity is determined on ^99mTc-MAA SPECT-CT dose results in order to avoid healthy parenchyma toxicity and to effectively irradiate the tumor. The assumption of identical radiopharmaceutical distribution between simulation and verification is still under debate and literature data showed controversial results. In this study 10 HCC patient's dosimetry performed on ^99mTc SPECT-CT and ⁹⁰Y PET-CT were compared. Patients were selected when a good agreement between the pre and post-therapy distribution was observed in order to investigate the intrinsic dosimetric variations between the two imaging modalities. Mean doses (MIRD and Voxel approaches) showed a good correlation (Pearson's coefficient r > 0.90) both for tumor and normal liver. Dose Volume Histogram curves were compared with a good agreement particularly for normal liver (D50). Goal doses were achieved for 90% of patients. Bland-Altman analysis indicates lower variations for healthy parenchyma than for tumor (1.96 SD equal to 9.1 Gy and 68 Gy respectively) confirming the robustness of the dose-toxicity approach. PET-CT dosimetry well correlates with SPECT-CT doses (under assumption of same catheter position and ⁹⁰Y activity). Better agreement was showed for 7/10 and 8/10 patients for T and NL respectively, confirming dosimetry as effective tool to optimize and individualize the treatment.

90Y radioembolization dosimetry using a simple semi-quantitative method in intrahepatic cholangiocarcinoma: Glass versus resin microspheres

INTRODUCTION

There are two different types of ⁹⁰Y Microspheres, glass and resin, in the market for ⁹⁰Y radioembolization (⁹⁰Y-RE). This study aimed to investigate the dose of radiation delivered through glass vs. resin-based ⁹⁰Y-RE to intrahepatic cholangiocarcinoma (ICC).

METHODS

In this retrospective study, 10 patients with ICC underwent ⁹⁰Y-RE, five underwent glass (Glass group) and other 5 resin (Resin group) microspheres. Technetium-99m macro-aggregated albumin (Tc-99m MAA) shunt study was performed two weeks before ⁹⁰Y-RE. Within 2 h from ⁹⁰Y-RE, Bremsstrahlung SPECT/CT was obtained. Regions of interest (ROIs) were segmented around the targeted tumor and the liver. Tumor and liver volumes, corresponding radioactive counts, and tumor to liver count ratio were calculated using MIM software and compared between Glass and Resin groups.

RESULTS

Mean hepatopulmonary shunt fraction was 7.1 vs. 6.2% for the Glass and Resin groups (p = 0.83), with no extrahepatic activity. There was no difference in the activity and tumor uptake of administered Tc-99m MAA between both groups (p = 0.71 and p = 0.63). Mean administered activity of ⁹⁰Y in the Glass group was higher than the Resin group (73.2 ± 24.3 vs. 44.5 ± 18.2 mCi, p < 0.001). The tumor ⁹⁰Y uptake was significantly higher in the Glass group compared to the Resin group (41.3% vs. 33.5%, p < 0.001), corresponding to the mean tumor dose of 205.7 ± 19.7 vs. 128.9 ± 10.6 Gy, respectively (p < 0.001). The tumor to normal liver parenchyma ⁹⁰Y dose ratio was significantly higher in the Glass group compared to the Resin group, 4.9 ± 0.7 versus 2.4 ± 0.3 respectably (p < 0.001).

CONCLUSIONS

Both ⁹⁰Y glass and resin-based microsphere ⁹⁰Y-RE are feasible and safe in patients with ICC, while ⁹⁰Y glass microsphere delivers higher dose of ⁹⁰Y to the targeted tumors.

ADVANCES IN KNOWLEDGE

While both ⁹⁰Y glass and resin-based microsphere yttrium-90 radioembolization are feasible and safe treatment options for in patients with intrahepatic cholangiocarcinoma, ⁹⁰Y glass microsphere delivers higher dose of ⁹⁰Y to the targeted tumors.

IMPLICATIONS FOR PATIENT CARE

Both of ⁹⁰Y glass and resin-based microsphere can be safely and feasibly used for treatment of intrahepatic cholangiocarcinoma, difference in dose of ⁹⁰Y delivered to the targeted tumors should be clinically considered while choosing the microsphere type.