Regional lymph nodes distribution pattern in central area of right-sided colon cancer: in-vivo detection and the update on the clinical exploration.

Distribution of regional lymph nodes (LNs) is decisive for the lymphadenectomy boundary in radical resection of right-sided colon cancer (RCC). Currently, the data of LNs in central area remains ambiguous and scarce. Herein we aim to provide a more detailed anatomical research on LNs surrounding the superior mesenteric vessels for RCC and investigated the metastasis rate. In this study, Carbon Nanoparticles (CNs) and Indocyanine Green (ICG) were used for regional LNs mapping by preoperative colonoscopic tattooing (PCT) and we laparoscopically observed the stained LNs distribution pattern. Lastly, 143 RCC patients who received a "superior mesenteric artery (SMA)-oriented" hemicolectomy were included to calculate the probability of LNs metastasis in our target area. 27 patients diagnosed as RCC (mean age 58.04 years, 17 male) were included. 14 patients underwent CNs injection and 13 patients consented to the ICG, while 4 cases suffered from imaging failure. The unequal number of the regional LNs located between SMV and SMA was detected in 22 cases (81.48%), posterior to SMV area in 6 cases (22.22%), and anterior to SMA in 16 cases (59.26%), respectively. The presence of LNs posterior to SMV was associated with the crossing pattern of ileocolic artery (χ2 = 4.24, P = 0.039). The probability of LNs metastasis in the above areas (target areas) was 2.10% (3/143). In conclusion, right-hemi colon-draining lymphatic vessels anteriorly/posteriorly traversed the SMV and arrived at the surface of SMA near the middle colonic artery (MCA) level, which highlights the potential need of removing mesenteric tissue in our target area on lymphatic resection. AJCR