Evaluation of the lymphatic flow at the splenic flexure in the laparoscopic colon cancer surgery

Jun Watanabe1, Mitsuyoshi Ota2, Yusuke Suwa1, Hirokazu Suwa2, Masashi Momiyama3, Atsushi Ishibe3, Kazuteru Watanabe4, HIdenobu Masui1, Kaoru Nagahori1. 1Department of Surgery, Yokosuka Kyosai Hospital, 2Department of Surgery, Gastroenterological Center, Yokohama City University, 3Department of Gastroenterological Surgery, Yokohama City University Graduate School of Medicine, 4Department of Surgery, NTT Medical Center

Background: Complete mesocolic excision (CME) and central vascular ligation (CVL) are nowadays state of the art in the treatment of colon cancer that provides improved oncologic outcomes. However, the treatment of colon cancer located in splenic flexure is not standardized because the lymphatic drainage at this site is variable. It is considered that carcinoma at this site has dual lymphatic drainage of the Middle colic artery (MCA) and left colic artery (LCA) areas and in addition, if it exists, accessory left colic artery (aLCA) area. There is no systematic data in the literature on the frequency of lymphatic drainage root.

Purpose: The aim of this study is to evaluate the lymphatic flow at the splenic flexure.

Methods: From July 2013 to June 2015, we enrolled consecutive patients of colon cancer located in splenic flexure with preoperative diagnosis of clinical N0. Primary outcome is frequency of the direction of lymphatic flow from splenic flexure. At first, we injected indocyanine green (2.5mg) to submucosal layer near the tumor and observed lymphatic flow using the laparoscopic near-infrared camera system in 30 minutes after injection.

Results: A total of 26 consecutive patients were enrolled in this study. These patients included 7 females, and had a mean age of 66.8 years, a mean body mass index of 23.3 kg/m2. A mean duration of operation was 220 minutes and a mean blood loss was 62 ml. The presence of aLCA rate was 38% (10 cases). The prevalence of direction of lymph flow type was 7 cases (26.9%) for LCA area, 5 cases (19.2%) for LCA and aLCA areas, 5 cases (19.2%) for MCA area, 3 cases (11.5%) for aLCA area, 2 case (7.7%) for MAC and aMCA areas. Lymph flow not accompanying artery directed to the root of IMV was 4 cases (15.4%). 0 case (0.0%) for LCA and MCA areas. There are 14 cases (53.8%) with lymph flow directed to the area of root of IMV if aLCA exist or not. a number of retrieved lymph nodes (LNs) was 17.6 and fluorescence LNs was 10.7. LN metastases were 6 cases, but were all lymph flow areas domain by the fluorescence lymphatic flow evaluation.

Conclusion: In CME and CVL for colon cancer located in splenic flexure, we should perform LN dissection of the root of IMV area plus LCA area or MCA area by the fluorescence lymphatic flow evaluation, and LN dissection of 3 areas is not necessary.

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