# Effect of disappearing liver metastases during pre-ablation chemotherapy on the prognosis of percutaneous microwave ablation in synchronous colorectal liver metastases patients

## TL;DR

This study shows that colorectal liver metastases that disappear during chemotherapy before microwave ablation are linked to worse liver cancer control, even though overall survival is not affected.

## Contribution

The study identifies that radiographic disappearance of liver metastases during chemotherapy is a risk factor for intrahepatic recurrence after microwave ablation.

## Key findings

- Patients with disappearing liver metastases had significantly lower intrahepatic progression-free survival compared to those without.
- Disappearing metastases were found to be a risk factor for poor intrahepatic progression-free survival in multivariable analysis.
- Overall survival was not significantly different between patients with and without disappearing metastases.

## Abstract

Disappearing colorectal liver metastases (DLM) frequently occur during chemotherapy. However, DLM is not equivalent to pathologically complete response. This study aimed to investigate the effect of radiographic DLM on microwave ablation (MWA) in patients with synchronous colorectal liver metastases (CRLM).

A retrospective review was performed for patients who accepted MWA following pre-ablation chemotherapy from January 2014 to December 2021. DLM was defined as undetectable tumors on pre-ablation contrast-enhanced imagings compared to the initial ones. Overall survival (OS) and intrahepatic progression-free survival (ihPFS) were analyzed and compared between patients with and without DLM. Univariate and multivariate cox regression were used to identify risk factors for OS and ihPFS. A propensity score matching (PSM) analysis was used to balance the patient demographics.

Sixty-eight patients with DLM and 97 without DLM were included. The 1-year, 3-year, and 5-year ihPFS rates were significantly lower for patients with DLM compared to those without DLM before and after PSM (55.7%, 36.8%, and 30.6% vs. 70.8%, 59.3%, and 52.0% before PSM, respectively, p = 0.012; 44.9%, 31.8%, and 21.2% vs. 72.3%, 58.8%, and 47.5% after PSM, respectively, p = 0.039). Twenty-three (33.8%) patients with DLM had DLM-site recurrences during follow-up. The OS was not statistically different between the two groups both before and after PSM (p-value = 0.11 and 0.49). Multivariable cox regression revealed DLM (HR = 2.2; 95% CI = 1.1–4.1; p-value = 0.009) was a risk factor for poor ihPFS.

Patients with DLM presented worse ihPFS, suggesting that to eradicate visible tumors before disappearance may be advantageous when synchronous CRLM is ablatable.