Abstract: Objective To evaluate the efficacy of ultrasound-guided microwave ablation (MWA) in treating patients with colorectal cancer liver metastases (CRLM) and to investigate the key factors influencing prognosis. Methods A retrospective analysis was conducted on the clinical data of 120 CRLM patients who underwent ultrasound-guided MWA at Peking University Shougang Hospital between June 2022 and June 2024. Outcome measures included the complete ablation rate, complication rate, local tumor progression (LTP) rate, progression-free survival (PFS), and overall survival (OS). Survival rates were calculated using the Kaplan-Meier method. Univariate analysis was performed using the Log-rank test, and multivariate analysis was conducted using a Cox proportional hazards regression model to identify independent prognostic factors. Results A total of 225 lesions were ablated in all patients. The initial complete ablation rate was 96.0%, and the major complication rate was 2.5%. After a median follow-up of 18.5 months, the LTP rate was 8.3%, and the median PFS was 14.0 months. The median OS was not reached by the end of the follow-up period, with a 1-year cumulative OS rate of 92.3%. Multivariate analysis identified failure to receive systemic chemotherapy, the presence of ≥3 liver metastases, and a maximum tumor diameter >3 cm as independent risk factors for shortened PFS. Conclusion Ultrasound-guided MWA is a safe and effective local treatment modality for CRLM. Active combination with systemic chemotherapy and effective control of intrahepatic tumor burden are key to improving patient prognosis.

Key words: Ultrasound, Microwave ablation, Colorectal liver metastases