Prognostic significance of intrahepatic lymphatic invasion in colorectal liver metastases

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. 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. 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