Interventional Treatments of Liver Metastases from Colorectal Cancer: Prognostic Factors and Subgroup Analyses

Background/Objectives: This secondary analysis aims to evaluate various prognostic factors for overall survival (OS) and hepatic progression-free survival (hPFS) and to perform subgroup analyses regarding OS of patients with unresectable and chemotherapy-refractory liver metastases from colorectal cancer (LMCRC) treated by the combination therapy of transarterial chemoembolization (TACE) and microwave ablation (MWA) or with MWA alone. Methods: A total of 251 patients with unresectable and chemotherapy-refractory LMCRC were included retrospectively. Group A consisted of 184 patients who received a combination of TACE and MWA. A total of 67 patients were included in group B, who received only MWA. Group C summarizes the total number of 251 patients treated. For all groups, the influence of age, sex, number of metastases, the diameter and volume of the largest metastasis, and the occurrence of recurrence on OS and hPFS was determined using univariate cox regression analysis. OS was compared between patients with more than three metastases and those with three or fewer, as well as between patients with a diameter of largest metastasis of 3 cm or less with patients with a diameter of largest metastasis of more than 3 cm. The analysis of OS was carried out using the Kaplan-Meier method. Results: For all three groups, the parameters of age, sex, number of metastases, diameter and volume of the largest metastasis, complete ablation status, and recurrence were not significant prognostic factors for OS. The number of metastases had a statistically significant influence on hPFS in group C (p = 0.034) and trended towards significance in group A (p = 0.057). The mean OS of patients with three metastases or less was in all groups longer than patients with more than three metastases, however, with no statistically significant differences (p = 0.83, 0.451 and 0.84 for groups A, B and C, respectively). There were no significant differences regarding OS between patients with diameter of largest metastasis of 3 cm or less compared to patients with diameter of largest metastasis more than 3 cm in all groups (p = 0.316, 0.812 and 0.45 for groups A, B and C, respectively). Conclusions: We could not observe significant prognostic factors in the treatment of LMCRC on OS. Accordingly, patients with three metastases or less had non-significant longer OS than patients with more than three metastases. The number of metastases had a significant impact on hPFS of the whole patient cohort and borderline significant impact on hPFS in patients treated with TACE combined with MWA.