To evaluate the efficiency and safety of transarterial chemoembolization (TACE) combined with microwave ablation (MWA, TACE-MWA) in patients with liver metastases from gastrointestinal cancers. To explore the ability of tumor burden score (TBS) in predicting the prognosis of patients with liver metastases after TACE-MWA.

This retrospective study involved 54 patients with liver metastases from gastrointestinal cancers who underwent TACE plus MWA between January 2015 and April 2020 in our hospital. Local tumor control, survival outcomes and complications were evaluated. TBS was used to evaluate the tumor burden of the patient. Patients were divided into low tumor burden group (TBS≤3, n = 24) and high tumor burden group (3 < TBS < 6, n = 30) and differences between the two groups were made. Time-dependent ROC analysis was conducted to evaluate the ability of TBS in predicting progression-free survival (PFS) and overall survival (OS).

The objective response rate (ORR) was 88.9% and the disease control rate (DCR) was 96.3% of the 54 patients. The median follow-up period was 21.5 months. Patients had a median PFS of 8.2 months and a median OS of 23.8 months. The 0.5-, 1- , 2-, and 3-year OS rates were 96.2%, 79.2%, 41.8%, and 24.3% respectively. The median PFS and OS were 9.8, 27.2 months in the low tumor burden group versus 6.6, 17.3 months in the high tumor burden group respectively (P < 0.05). Time-dependent ROC analysis showed that the AUC of TBS for predicting PFS and OS were 0.720 and 0.606, higher than that of maximum tumor diameter (0.695 and 0.575) and tumor number (0.586 and 0.483). No major complication related to treatment was observed in the two groups.

TACE-MWA is a safe and effective treatment option for patients with liver metastases from gastrointestinal cancers with improved disease control and prolonged overall survival. TBS may be a good tool for predicting the prognosis of patients with liver metastases after TACE-MWA.