The Burden of Hepatocellular Carcinoma in Singapore
Hepatocellular carcinoma (HCC), the most common type of primary liver cancer, poses a significant health challenge in Singapore. Despite advances in screening and vaccination against hepatitis B virus (HBV), which is a leading cause of HCC here, the disease remains a major concern. According to recent data from the Singapore Cancer Registry, liver cancer accounts for a substantial portion of cancer diagnoses, with around 50 new cancer cases reported daily across all types, and liver cancer contributing notably due to its aggressive nature. The age-standardized incidence rate has stabilized in recent decades, but projections indicate a potential rise with increasing non-alcoholic fatty liver disease linked to metabolic syndrome. In Singapore's multi-ethnic population, HCC disproportionately affects males and those with chronic liver conditions, underscoring the need for innovative therapies like transarterial radioembolization (TARE), also known as selective internal radiation therapy (SIRT) with yttrium-90 (Y-90) microspheres.
Understanding Y-90 Radioembolization for HCC Treatment
Y-90 radioembolization involves injecting tiny glass or resin microspheres loaded with the radioactive isotope yttrium-90 into the hepatic artery feeding the liver tumor. These microspheres lodge in the tumor's capillary bed, delivering high-dose radiation locally while minimizing exposure to healthy tissue. In Singapore, institutions like the National Cancer Centre Singapore (NCCS) and Singapore General Hospital (SGH) have pioneered this therapy, treating over 800 unresectable HCC cases since 2008. This approach is particularly valuable for patients ineligible for surgery or ablation, offering tumor control rates exceeding 80% in intermediate-stage disease. However, precise dosimetry—calculating the radiation dose to both tumor and nontumorous liver—is critical to balance efficacy and safety.
What is Radioembolization-Induced Liver Disease (REILD)?
Radioembolization-induced liver disease (REILD) is a rare but potentially fatal complication characterized by jaundice, ascites, and liver failure typically 4-8 weeks post-treatment. Unlike classical radiation-induced liver disease (RILD) from external beam radiotherapy, REILD stems from microvascular endothelial damage in healthy liver parenchyma. Global incidence ranges from 0-8%, with lethality up to 5% in severe cases. Risk factors include whole-liver treatment, underlying cirrhosis, high tumor burden, and prior chemotherapy. In Singapore's context, where many HCC patients have HBV-related cirrhosis, preventing REILD is paramount to expanding TARE's role in curative pathways.
The Landmark SingHealth Duke-NUS AMRI REILD Study
Led by researchers from the Academic Medicine Research Institute (AMRI) under SingHealth Duke-NUS, including Joanna Rui En Fong, Kaina Chen, and Aaron Kian Ti Tong, this propensity score-matched analysis examined hepatic adverse events post-Y-90 resin microsphere TARE in HCC patients at SGH. Published in Nuclear Medicine Communications in early 2026, the study scrutinized dosimetry parameters against clinical outcomes, challenging established safety thresholds. By matching cohorts for baseline characteristics, it isolated the impact of radiation dose and patient factors on liver toxicity, providing robust evidence from one of Asia's largest TARE cohorts.
Challenging Conventional Dose Thresholds
A pivotal revelation was severe liver toxicity occurring at absorbed doses to nontumorous liver below the conventional safe limit of 70 Gy. The study documented cases where toxicity manifested despite conservative dosing, prompting reevaluation of partition models used in pre-treatment planning. Median nontumorous liver dose in REILD cases was notably lower at around 33 Gy, suggesting hypersensitivity in certain patients. This finding urges personalized dosimetry incorporating tumor burden and vascular flow beyond standard MAA SPECT simulations.
Photo by Tianqi Yang on Unsplash
- Doses below 70 Gy still triggered grade 3+ toxicities in vulnerable livers.
- Bilobar treatments doubled REILD risk compared to unilobar.
- Post-procedural monitoring intensified for high-risk profiles.
ALBI Score: A Superior Predictor of Toxicity Risk
The albumin-bilirubin (ALBI) score, calculated as (log10 bilirubin × 0.66) + (albumin g/L × −0.085), emerged as a reliable predictor. Patients with ALBI grade ≥2 (moderate-poor liver function) faced significantly higher post-TARE toxicities. Unlike Child-Pugh, ALBI avoids subjective ascites/encephalopathy assessments, making it ideal for precise risk stratification. In the cohort, ALBI ≥2 correlated strongly with REILD incidence (p<0.05), enabling clinicians to tailor therapy or opt for alternatives like TACE.Read the full study on PubMed.
Clinical Implications for Singapore's HCC Management
At NCCS and SGH, this research refines protocols: pre-TARE ALBI screening now flags grade ≥2 patients for dose reduction or staging. A related SGH/NCCS study advocated higher tumor doses (>150 Gy) for better survival (up to 15 months gain) while respecting nontumorous limits. Downstaging 17% of cases to surgery boosts curative potential, aligning with Singapore's precision oncology push. Multidisciplinary tumor boards integrate these insights, enhancing outcomes in HBV-endemic settings.
AMRI's Role in Academic Medicine Excellence
The SingHealth Duke-NUS Academic Medical Centre (AMC), through AMRI, exemplifies translational research. As a research enabler, AMRI supports clinician-scientists bridging lab-to-bedside. Duke-NUS, Singapore's only graduate medical school, trains PhD/MD researchers tackling HCC via programs like the Programme in Translational and Clinical Liver Research led by Prof. Pierce Chow. This ecosystem has positioned Singapore as an Asia-Pacific hub for interventional oncology trials.
Prevention Strategies and Future Outlook
Emerging strategies include ursodeoxycholic acid prophylaxis (though mixed evidence), advanced PET/MRI dosimetry, and AI predictive models. Ongoing AHCC trials at NCCS explore TARE combinations. Singapore's National Precision Medicine initiative may integrate ALBI-genomics for risk profiling. Long-term, these discoveries could reduce REILD to <2%, expanding TARE to earlier stages.
- Enhanced pre-treatment liver volumetry.
- ALBI-guided patient selection.
- Prospective validation trials planned.
Stakeholder Perspectives and Real-World Impact
Oncologists at SGH emphasize ALBI's simplicity for busy clinics, while patients benefit from safer therapies enabling downstaging. Policymakers note cost savings from avoided transplants. Duke-NUS students gain hands-on exposure via AMRI mentorship, fostering next-gen researchers.
Training the Next Generation of Researchers
Duke-NUS's PhD programs in cancer biology equip trainees with skills for dosimetry innovation. Collaborations with NCCS yield case studies for residents, emphasizing evidence-based practice amid rising HCC.