Clinical professor Seoul National University Hospital, Republic of Korea
Purpose: To evaluate the safety and efficacy of streamlining radioembolization using yttrium-90 resin microspheres without lung shunt fraction (LSF) assessment in patients with colorectal liver metastases (mCRC) smaller than 7 cm.
Materials and Methods: This single-center retrospective study included 32 patients with mCRC who underwent radioembolization between June 2021 and April 2025. Eligibility criteria were: target tumor < 7 cm, no prior local therapy, treatment with resin microspheres, omission of LSF measurement, and at least one follow-up image. Radiation activity was prescribed based on tumor location, liver function, and clinical setting, using both single-compartment and partition dosimetry. Post-treatment Y-90 PET/CT dosimetry was performed in 15 patients. Clinical outcomes, tumor response, and treatment-related toxicity were analyzed.
Results: Median administered activity was 0.50 GBq (IQR, 0.41–0.82). Median mean absorbed dose (mAD) to perfused tissue was 136 Gy, and median tumor absorbed dose (TAD) was 347 Gy by partition dosimetry. Post-treatment PET/CT analysis (n=15) showed a median TAD of 432 Gy with a median tumor-to-normal ratio of 3.9, demonstrating moderate correlation with estimated partition dosimetry (r=0.65, p=0.009). Median follow-up was 16.2 months. The best tumor responses were complete response in 12.5%, partial response in 59.4%, and stable disease in 28.1%. One- and two-year local tumor progression-free survival rates were 67.9% and 52.8%, respectively, with a median overall survival of 22.7 months. No patient developed radiation pneumonitis or radioembolization-induced liver disease.
Conclusion: Streamlining radioembolization without LSF assessment appears safe and effective for patients with mCRC < 7 cm, achieving favorable tumor control and survival outcomes with low toxicity.
