Preliminary Analysis of Liquid Biopsy after Hepatectomy for Colorectal Liver Metastases

Abstract

Liquid biopsies are increasingly tested in patients with colorectal cancer to assess tumor burden, response to therapy, and prognosis. The significance of liquid biopsy results after resection of colorectal liver metastases (CLMs) is not well-defined. Sixty-three patients undergoing CLM resection between 2016 and 2018 had plasma drawn postoperatively for liquid biopsy evaluation. Next-generation sequencing analysis was performed to detect somatic mutations in 70 genes. Liquid biopsy after CLM resection was positive in 42 of 63 patients (67%). Eleven patients (18%) had 1 gene mutation, 14 patients (22%) had 2 to 3 mutations, and 17 patients (27%) had 4 or more mutations. The most common mutation was APC, detected in 32 patients (76%), followed by TP53 (74%) and KRAS (38%). Two-year overall survival rate from date of liver resection was significantly worse among patients with a positive liquid biopsy (70% vs 100%; p= 0.005), particularly for those with 4 or more gene mutations detected, whose 2-year overall survival rate was 41%. Sixteen of the 63 patients underwent serial liquid biopsies, resulting in 100 liquid biopsies with matched serum CEA and CT scan results. Metastases were identified in 74 CT scans, which correlated with positive liquid biopsy in 77% of samples (p < 0.001) and CEA > 3 ng/mL in 45% of samples (p < 0.22). Liquid biopsy results provide information about disease burden and prognosis that is complementary to serum CEA and CT imaging. A positive liquid biopsy after CLM resection is associated with worse overall survival, particularly when multiple gene mutations are detected.