Microwave ablation for colorectal cancer metastasis to the liver: a single-center retrospective analysis

Abstract

Background: The purpose of this study is to evaluate the safety and intermediate-term efficacy of percutaneous microwave (MW) ablation for the treatment of colorectal liver metastases (CRLM) at a single institution.

Methods: A retrospective review was performed of all CRLM treated with MW ablation from 3/2011 to 7/2020 (102 tumors; 72 procedures; 57 patients). Mean age was 60 years (range, 36-88) and mean tumor size was 1.8 cm (range, 0.5-5.0 cm). The patient population included 19 patients with extra-hepatic disease. Chemotherapy (pre- and/or post-ablation) was given in 98% of patients. Forty-five sessions were preceded by other focal CRLM treatments including resection, ablation, radiation, and radioembolization. Kaplan-Meier curves were used to estimate local tumor progression-free survival (LTPFS), disease-free survival (DFS), and overall survival (OS) and multivariate analysis (Cox Proportional Hazards model) was used to test predictors of OS.

Results: Technical success (complete ablation) was 100% and median follow-up was 42 months (range, 1-112). There was a 4% major complication rate and an overall complication rate of 8%. Local tumor progression (LTP) rate during the entire study period was 4/98 (4%), in which 2 were retreated with MW ablation for a secondary LTP-rate of 2%. LTP-free survival at 1, 3, and 5 years was 93%, 58%, and 39% and median LTP-free survival was 48 months. OS at 1, 3, and 5 years was 96%, 66%, 47% and median OS was 52 months. There were no statistically significant predictors of OS.

Conclusions: MW ablation of hepatic colorectal liver metastases appears safe with excellent local tumor control and prolonged survival compared to historical controls in selected patients. Further comparative studies with other local treatment strategies appear indicated.

Keywords: Colorectal cancer; ablation; hepatic metastasis; liver targeted therapy; treatment of metastasis.

Figure 1

Overall survival Kaplan-Meier curve with 95% confidence bands.

Figure 2

Overall survival Kaplan-Meier analysis for predicting factors that influence OS. OS, overall survival.

Figure 3

Disease-free survival Kaplan-Meier curve with 95% confidence bands.

Figure 4

Local tumor progression free survival Kaplan-Meier curve with 95% confidence bands.

Figure 5

Example of local tumor progression with retreatment. (A) Segment VIII lesion in a 62-year-old male is radiographically occult on CT but visible by ultrasound. (B,C) US of lesion (yellow arrow) without and with US contrast. (D) Intra-procedural US demonstrating gas bubbles covering entire lesion (green arrow), and (E) post-ablation CT of lesion demonstrating appropriate coverage (green arrow). (F) New area of nodular enhancement detected along the medial ablation margin (orange arrow) 3 months post-ablation, consistent with LTP. (G) Repeat ablation shows appropriate coverage of LTP (orange arrow) without residual enhancing tissue. (H) Follow-up scan 4 months after re-treatment demonstrates no recurrence (orange arrow). LTP, local tumor progression.