High-intensity focused ultrasound ablation combined with systemic therapy for unresectable colorectal cancer liver metastasis: A propensity score-matched analysis

Objective: Unresectable colorectal cancer liver metastasis (CRLM) remains a challenging obstacle that often prevents curative treatment. In this study, we retrospectively analyzed the efficacy and safety of high-intensity focused ultrasound (HIFU) as a local adjuvant therapy for systemic chemotherapy for patients with unresectable CRLM. HIFU is a noninvasive method previously demonstrated as efficacious for various solid malignancies.Methods: Propensity score matching was used for the combination therapy group (HIFU group, n = 59) and the observation group receiving systemic therapy only (No-HIFU group, n = 59). In addition, the survival benefit, adverse effects, and factors affecting prognosis following HIFU were evaluated.Results: The disease control rate was 77.9% and 62.7%, and the objective remission rate was 18.9% and 6.8% in the HIFU and non-HIFU groups, respectively. The survival analysis showed that median progression-free survival (mPFS) was 12.0 months and 11.0 months for the HIFU and non-HIFU groups, respectively (p = 0.002). The univariate and multivariate analysis showed that pre-treatment colorectal cancer liver metastasis lesion size was significantly associated with mPFS. In addition, patients that received a combination treatment for CRLM lesions <5.0 cm had a longer mPFS when compared to those receiving systemic therapy alone (13.0 months vs. 11.0 months, p = 0.001). In the HIFU group, patients with lesions <5.0 cm had a longer mPFS than patients with lesions >= 5.0 cm (13.0 months vs. 10.0 months, p = 0.04) (Figure 3B,C). Most treatment-related adverse events observed in both groups were grade 1-2. Only four cases (6.8%) of grade 1-2 skin burns were observed in patients in the HIFU group; no other statistically significant adverse events were observed.Conclusions: Our study showed that HIFU ablation targeting unresectable CRLM alongside systemic therapy safely and significantly improved local control rates and prolonged mPFS, especially for lesions smaller than 5.0 cm.