Liver transplantation for unresectable colorectal liver metastases: Pooled real-world data from all Belgian liver transplant centers.

20 Background: Liver transplantation (LTx) for unresectable colorectal liver metastases (uCLM) has gained renewed interest following the 2024 TransMet trial, which provided prospective, randomized evidence supporting its role in selected patients. This increased demand for LTx in Belgium despite the absence of a national protocol in this early adoption phase. Given the modest number of patients transplanted in TransMet (38), SECA-I (21) and SECA-II (15), and the heterogeneity in selection criteria, we retrospectively collected and analyzed all Belgian LTx cases for uCLM to date. Although performed without a uniform protocol, this national, multi-center cohort provides a timely snapshot of clinical practice prior to launching a standardized national framework. Our aim was to consolidate real-world data to inform future practice and to contribute to the international policy making on this emerging LTx indication. Methods: This multicenter retrospective study included all LTx cases for uCLM performed across all six accredited Belgian LTx centers. Patient selection followed local protocols that varied. In all cases, CLM were classified as permanently unresectable and there was no prior extrahepatic disease. Results: Between June 2016 and August 2025, 29 patients underwent LTx for uCLM in Belgium. Median age was 56 years (IQR 50–61), with 69% male. Primary tumors were mostly left-sided (79%). All tumors were MSS; 86% were RAS/BRAF wild type, 7% had a KRAS - and 7% a BRAF mutation. Prior to LTx, patients received a median of 22 chemotherapy cycles (IQR 16–28), in up to two lines of treatment. The first line consisted of a doublet (62%) or triplet (38%) regimen; 93% received targeted therapy. Serious adverse events after LTx occurred in 62%, including three acute rejections and one intraoperative death; no re-transplantations were performed. Median follow-up was 20.5 months (IQR 7.0–35.3). Recurrence occurred in 38%, mainly pulmonary (73%) and peritoneal (27%), with median time to recurrence 6.3 months (IQR 5.3–6.7). 2-year progression-free survival (PFS) was 35.7% (95% CI 12.8–64.9) among 14 patients eligible for analysis; 1-year PFS was 47.6% (95% CI 25.7–70.2) among 21 patients. 2-year overall survival (OS) was 53.3% (95% CI 43.3–74.1) among 15 patients eligible for analysis; 1-year OS was 68.2% (95% CI 45.6–85.8) among 22 patients. Conclusions: LTx for uCLM is feasible in Belgian practice, with encouraging short-term outcomes despite heterogeneous selection criteria and short follow-up. However recurrence was high despite the limited timeframe, though no hepatic recurrences were observed. These retrospective findings should be interpreted cautiously but support further uptake of LTx in clinical practice, while emphasizing the importance of a standardized national protocol for patient selection to improve long-term outcomes.