# Prognostic role of tumour volume and downstaging response on outcome after liver transplantation for colorectal liver metastases: retrospective study

## TL;DR

This study shows that reducing tumor volume below 35 mL before liver transplantation improves survival in patients with colorectal liver metastases.

## Contribution

The study identifies a 35 mL tumor volume threshold as a novel prognostic marker for liver transplant outcomes in colorectal liver metastases.

## Key findings

- A tumor volume below 35 mL before transplantation was linked to significantly better 5-year survival.
- Heterogeneous tumor response to chemotherapy was associated with poor prognosis and no survival beyond 2.16 years.
- Patients who achieved the 35 mL threshold through downstaging had outcomes similar to those with naturally low tumor burden.

## Abstract

The incidence of colorectal cancer is increasing, and the liver remains the predominant site for metastases. Whereas liver resection is the standard treatment for colorectal liver metastases (CRLMs), liver transplantation (LT) has re-emerged as a viable option for selected patients. The aim of this study was to investigate whether tumour volume and changes in tumour volume during chemotherapy before transplantation predict overall survival.

Patients who underwent LT for CRLMs between November 2006 and August 2020 were included. Tumour volumes were measured via manual segmentation on computerized tomography scans at baseline, at maximum tumour volume, and immediately before LT. Response to chemotherapy was assessed using Response Evaluation Criteria in Solid Tumours (RECIST) criteria, and the heterogeneous response was noted to investigate whether this subgroup performs differently. Receiver operating characteristic analysis was conducted to determine a tumour volume cut-off value for predicting overall survival. Overall survival between groups was compared using Kaplan–Meier curves and log rank test.

Fifty-nine patients who underwent LT for CRLMs were analysed retrospectively. Receiver operating characteristic analysis revealed that final tumour volume at time of LT was a strong predictor of 5-year overall survival (area under the curve= 0.789), with a 35 mL cut-off providing optimal clinical discrimination. Patients achieving a final tumour volume below 35 mL, either consistently or via downstaging, demonstrated significantly improved survival compared with those with persistently high tumour volumes (4.54 years versus 2.17 years; P < 0.001). Heterogeneous responses to chemotherapy were associated with poorer prognosis with no patients surviving beyond 2.16 years (P < 0.001).

Dynamic tumour assessment, particularly measuring tumour volume to below 35 mL, is an important prognostic marker in LT for CRLMs.

This study evaluates the prognostic role of tumour volume and response to downstaging in 59 patients undergoing liver transplantation for colorectal liver metastases. A tumour volume threshold of 35 mL before transplantation was associated with improved 5-year survival, and patients who reached this threshold through successful downstaging had outcomes comparable to those with consistently low tumour burden. Heterogeneous lesion response to chemotherapy identified patients at higher risk, highlighting the value of volumetric and dynamic tumour assessment in patient selection.