Pre-hepatectomy dynamic circulating tumor DNA to predict pathologic response to preoperative chemotherapy and post-hepatectomy recurrence in patients with colorectal liver metastases

Objective To evaluate the predictive value of pre-hepatectomy dynamic circulating tumor DNA (ctDNA) on pathologic response to preoperative chemotherapy and recurrence after liver resection for colorectal liver metastases (CRLM). Background Pathologic response is a predictor of clinical outcomes for patients undergoing hepatectomy for CRLM. Postoperative ctDNA has been proven to be sensitive for recurrence detection. However, few studies investigate the impact of pre-hepatectomy ctDNA on pathologic response and recurrence. Methods Patients with potential resectable CRLM underwent preoperative chemotherapy and hepatectomy between 2018 and 2021 was considered for inclusion. Plasma ctDNA was collected before and after preoperative chemotherapy. Pathologic response was analyzed for all patients after liver resection. Recurrence free survival was compared between patients with different ctDNA status and different pathologic response. The relation between ctDNA and pathologic response was also analyzed. Results A total of 114 patients were included. ctDNA was detectable in 108 of 114 patients (94.7%) before chemotherapy, in 56 of 114 patients (49.1%) after chemotherapy. Patients with ctDNA positive at baseline and negative after chemotherapy had significantly longer RFS (median RFS 17 vs 7 months, p = 0.001) and HRFS (median HRFS unreached vs 8 months, p < 0.001) than those with ctDNA persistently positive after chemotherapy. Two patients (1.6%) had a pathologic complete response and 56 patients (45.2%) had a pathologic major response. Post-chemotherapy ctDNA- was associated with improved major pathologic response (53.4% vs 32.1%, p = 0.011). In the multivariable analysis, ctDNA- after chemotherapy (HR 0.51, 95% CI 0.28-0.93), major pathologic response (HR 0.34, 95% CI 0.19-0.62) and surgery combined with radiofrequency ablation (HR 2.62, 95% CI 1.38-5.00) were independently associated with RFS (all p < 0.05). Conclusions Pre-hepatectomy dynamic monitoring of ctDNA could predict pathologic response to preoperative chemotherapy and post-hepatectomy recurrence in CRLM patients. Negative ctDNA after preoperative chemotherapy was associated with better tumor regression grade and recurrence-free survival, which might be used to guide pre-hepatectomy chemotherapy and predict prognosis.