Prognostic significance of intrahepatic lymphatic invasion in colorectal liver metastases.

Background: Intrahepatic lymphatic invasion is an adverse prognostic factor after hepatectomy for colorectal liver metastases (CLMs). However, most patients in previous reports had liver resection before the era of FOLFOX/FIRI-based chemotherapy.

Methods: Forty-six patients who underwent hepatectomy for CLMs from 2004 to 2020 were evaluated. We histologically evaluated portal invasion, intrahepatic lymphatic invasion, and biliary invasion on hematoxylin-eosin slides. We also collected the following clinicopathologic factors: gender, age, timing, the number and maximum size of CLMs, preoperative tumor markers, neutrophil/lymphocyte ratio, location, and lymph node metastases of primary cancer, and chemotherapy after hepatectomy. A multivariate Cox proportional hazard model was used to define the relationship between overall (OS) or disease-free survival (DFS) and clinicopathologic factors.

Results: Histological invasions were portal invasion in 8 (17.4 %), intrahepatic lymphatic invasion in 6 (13.0 %), and biliary invasion in 5 (10.9 %). Chemotherapy for recurrence after hepatectomy (n = 29) was performed in 22 and 14 of those who received FOLFOX/FIRI-based chemotherapy. By multivariate analysis, the number of CLMs (p < 0. 01) and presence of intrahepatic lymphatic invasion (p = 0.02) were independent predictors of recurrence. The number of CLMs (p = 0.02) and prehepatectomy carcinoembryonic antigen level (p = 0.02), but not intrahepatic lymphatic invasion (p = 0.18), were independent predictors of survival using multivariate analysis.

Conclusions: The presence of intrahepatic lymphatic invasion adversely affected patient's DFS, but not OS in patients with CLMs in the era of FOLFOX/FIRI chemotherapy. FOLFOX/FIRI-based chemotherapy might improve OS, even in patients with positive intrahepatic lymphatic invasion.