Tumor absorbed dose and outcomes after Y-90 glass radioembolization for colorectal liver metastases: does dose escalation improve survival in real-world practice?

PURPOSE: To assess the dose-response and dose-survival outcomes of yttrium-90 (Y90) transarterial radioembolization (TARE) using Therasphere microspheres in patients with colorectal cancer liver metastases (CRCLM). MATERIAL AND METHODS: Between May 2014 and December 2024, patients with chemorefractory CRCLM who underwent Y90 TARE using glass microspheres were retrospectively included. Patients were divided into two groups according to tumour absorbed dose (TAD): TAD<189 Gy (group 1) and TAD ≥189 Gy (group 2). The primary outcomes were overall survival (OS) and hepatic progression-free survival (hPFS). The secondary outcome was the objective response rate (ORR). RESULTS: A total of seventy-eight patients with a mean age of 69.9±11.2 years (range 41 to 91 years) were included. The median tumor dose and the median OS were 171.5 Gy (IQR; 147-200 Gy) and 8.9 months ( IQR; 5-14 months), respectively. The median TAD for groups 1 (n=46) and 2 (n=32) was 150 Gy (IQR; 122-166 Gy) and 202 Gy (IQR; 195-232 Gy), respectively. The median OS and hPFS for group 1 versus group 2 were 9.4 months (IQR; 6.7-17.7 months) and 5.2 months (IQR; 4-6.7 months) versus 7.1 months (IQR; 5-10.7 months) and 5.5 months (IQR; 4.2-6.7 months), respectively and were not significantly different (p = .107 and p = .663, respectively). The ORR did not differ significantly between the two groups (p = .943). CONCLUSION: In a real-world population of heavily pretreated patients with CRCLM, escalation of TAD beyond 189 Gy did not translate into improved survival, highlighting the dominant impact of advanced disease burden and extrahepatic progression.