Risk factors for extrahepatic metastasis after microwave ablation of hepatocellular carcinoma.

[BACKGROUND] Extrahepatic metastasis (EHM) of hepatocellular carcinoma (HCC) is associated with poor prognosis. However, the clinical characteristics and risk factors for EHM after microwave ablation (MWA) remain unclear.

[OBJECTIVE] To clarify the characteristics and risk factors for EHM after MWA in HCC patients.

[METHODS] This retrospective study enrolled 513 patients who were diagnosed with HCC between January 2010 and October 2023 at the Chinese PLA General Hospital, where microwave ablation was the primary treatment option. Univariate and multivariate analyses were used to identify the risk factors for EHM. Cumulative rates of EHM were estimated the Kaplan-Meier method.

[RESULTS] A total of 513 patients (mean age, 61 years ± 11; 384 males) were included, of whom 54 patients (10.52%) developed EHM. In the multivariate analysis, a tumor size between 2 and 5 cm [OR: 4.40;  = 0.005] and > 5 cm [OR: 11.67;  < 0.001], and a number of biopsies [OR: 1.32;  = 0.022] were significant risk factors for EHM. The occurrence rate of EHM decreased significantly after the implementation of needle track occlusion (6.55% vs. 54.55%,  < 0.001) and immunotherapy combined with the targeted therapy (2.00% vs. 13.72%,  = 0.02).

[CONCLUSION] Tumor size and the number of biopsies were the high risk factors for EHM in HCC patients treated with MWA. Needle track occlusion and the use of immunotherapy combined with targeted therapy can effectively reduce the incidence of EHM.