Distribution of lymph nodes – how deep is it TME necessary?

Abstract

Introduction: Standardization of TME had a great impact on decreasing local recurrence rates for the treatment of rectal cancer. However, number and distribution of lymphnodes along the mesorectum remains controversial. In order to confirm lower frequency of distal lymph nodes in the mesorectum we performed a cadaveric study. Patients and Methods:18 fresh cadavers were included in the study. The rectum was removed along with total mesorectal excision by an abdominal median incision. The fatty tissue of the mesorectum was divided into lateral-right, posterior and lateral-left portions. These segments were subdivided into proximal to distal levels (1-3). Histological confirmation was performed after complete lymphnodes dissection. Results: Overall, the mean number and size of lymph nodes/rectum was5.0±3.7 and 3±2.7mm. There was no association between the mean number or size with gender,BMI or age. There was a significantly higher prevalence of posterior LN location (2.8 LN/patient)as opposed to lateral locations (0.8 and 1.2 LN/patient; p=0.02). There was similar distributionof LN/patient between different rectal levels. Conclusions: Lymph nodes in the mesorectal tissue are predominantly small and posteriorly located. There is no decrease in the number of lymphnodes in the most distal third of the mesorectum.