Patterns of recurrence after ablation of colorectal cancer liver metastases

Purpose. To determine the local recurrence rate and factors associated with recurrence after intraoperative ablation of colorectal cancer liver metastases. Methods. A retrospective analysis of a prospectively maintained database was performed for patients who underwent ablation of a hepatic colorectal cancer metastasis in the operating room from April 1996 to March 2010. Kaplan-Meier survival curves and Cox models were used to determine recurrence rates and assess significance. Results. Ablation was performed in 10% (n = 158 patients) of all cases during the study period. Seventy-eight percent were performed in conjunction with a liver resection. Of the 315 tumors ablated, most tumors were ≤1 cm in maximum diameter (53%). Radiofrequency ablation was used to treat most of the tumors (70%). Thirty-six tumors (11%) had local recurrence as part of their recurrence pattern. Disease recurred in the liver or systemically after 212 tumors (67%) were ablated. On univariate analysis, tumor size greater than 1 cm was associated with a significantly increased risk of local recurrence (hazard ratio 2.3, 95% confidence interval 1.2-4.5, P = 0.013). The 2 year ablation zone recurrence-free survival was 92% for tumors ≤1 cm compared to 81% for tumors >1 cm. On multivariate analysis, tumor size of >1 cm, lack of postoperative chemotherapy, and use of cryotherapy were significantly associated with a higher local recurrence rate. Conclusions. Intraoperative ablation appears to be highly effective treatment for hepatic colorectal tumors ≤1 cm.