Pretransplant metabolic tumor volume predicts recurrence following liver transplantation for colorectal metastasis: A multicenter study

Liver transplant (LT) for colorectal cancer liver metastases (CRLM) is increasingly popular, yet the ideal selection criteria remain unknown. Pretransplant positron emission tomography (PET) metabolic tumor volume (MTV) has been described as predicting recurrence, with a proposed cutoff of MTV ≥70 cm 3 . This approach has not been validated. Patients undergoing LT for CRLM at 2 academic transplant centers (January 1, 2017, to December 1, 2023) were included. PET-MTV was calculated by a staff radiologist from the most recent PET-scan before LT using the published protocol. Twenty-six patients were included. Median follow-up was 609 days (IQR 320-1069) and from PET to LT was 1.9 months (1.3-2.6). Nearly all (n=24, 92.3%) received living donor transplantation. Absolute recurrence rate was 30.8% (n=8). Actuarial unadjusted 1- and 2-year recurrence-free survival (RFS) were 83% (n=15/18) and 62% (n=8/13); 1- and 2-year overall survival were 100% (n=18/18) and 85% (n=11/13). The incidence of recurrence-per-year follow-up was 0.35 when MTV ≥70 cm 3 versus 0.10 if MTV <70 cm 3 ( P <0.001). Median RFS using Kaplan-Meier product-estimate was 0.83 years (95% CI: 0.43-1.23) in MTV≥70 cm 3 versus 4.1 years (95% CI: 2.90-5.22) when MTV<70 cm 3 ( p <0.001); this was also associated with improved overall survival ( p =0.003). MTV>70 cm 3 demonstrated HR=2.42 (95% CI: 2.2-62.2, p =0.006) for association with RFS on univariate Cox-proportional hazards analysis, and an AUC=0.771 (95% CI: 0.560-0.981) for predicting recurrence ( p =0.030). Nineteen patients (69.2%) had histologically viable tumors, which were associated with recurrence (43% vs. 0%, p =0.039) and reduced RFS (log-rank p =0.019). PET-MTV was associated with the presence of histologically viable tumor (AUC=0.763, 95% CI: 0.583-0.944). PET-MTV ≥70 cm 3 was associated with reduced RFS and overall survival after LT for CRLM, confirming findings from the Norway group. This is likely due to its ability to identify residual viable tumors, which are independently associated with recurrence. PET-MTV should be a key selection criterion prior to LT for CRLM.