P-291 Missing colorectal liver metastases after neoadjuvant chemotherapy: Can we improve the prognosis?

Complete disappearance of colorectal liver metastases (CLM) after chemotherapy is considered a good prognostic factor of survival, but the presence of residual tumoral cells arrives to 80% and recurrence rate to 75% of patients. Nowadays, the management of these patients is still controversial. The aim of this study is to evaluate the impact of different onco-surgical strategies in the management of missing metastases after chemotherapy (MM) for patients who undergo a curative surgery. This retrospective single-center study (1999-2019) includes 69 patients with ≥1 MM. The patients have been divided into 2 groups: Patients with hepatic arterial infusion (HAI) of chemotherapy (HAI group) and patients without HAI chemotherapy (non-HAI) after surgery. Overall survival (OS), progression free survival (PFS), liver recurrence (LiR) and local recurrence (LoR) have been analyzed in each group. In total, 312 MM of 779 initial CLM have been identified with a median number of 2 (1-5) MM/patient. Ten patients (14%) were resected of original site of MM with a complete pathological response rate (TRG1) of 20% (n=2). 5y-LiR rate was 55% vs 79% (NS) for both groups (HAI and non-HAI groups). The 5y-PFS and 5y-OS were of 51% vs 38% et 59% vs 65% for the HAI and non-HAI groups (NS). Highly chemo sensitive patients who present MM have favorable long-term outcomes in survival. The high rate of residual tumoral cells in resected metastases makes consider that resection of original sites of MM is strongly recommended when it is possible. HAI chemotherapy after surgery does not significantly decrease the risk of local and hepatic recurrence in these patients presenting a great response to chemotherapy.