Location of liver metastases reflects the site of the primary colorectal carcinoma.

Objective: The present study was designed to investigate whether the different venous return of different locations of colorectal carcinomas affects the lobar distribution of metastases to the liver, due to the "streaming" within the portal vein.

Material And Methods: The site of the primary colorectal carcinoma was divided into the right- and left hemicolon according to the different venous drainage via the superior and the inferior mesenteric/splenic vein. Both groups were analyzed for the distribution of the metastases in the liver. The anatomic site of the liver metastases was detected by intraoperative exploration and differentiated between the two lobes using the Cantlie line.

Results: Out of a total of 178 patients, 109 men and 69 women with 264 metastases were eligible for the study. The ratio of metastases in the right and left hemiliver was 3.6:1 for 35 right-sided primary tumors (p=0.002) compared with 2.1:1 for 143 left-sided primary tumors (p=NS). No significant differences were evident for the sub-analysis of involved liver segments.

Conclusions: The results of our study support the existence of the "streaming" effect in the portal vein. Right-sided colon carcinomas predominantly involve the right hemiliver, while left-sided colon carcinomas involve the liver homogeneously, considering the size ratio of the right to left liver lobe, which is about 2:1. Knowledge of streaming may help us to understand the spread of abdominal malignancies and may provide a reference concerning the possible primary site depending on metastatic distribution in the liver.