BACKGROUND: The recommended operation for cecum cancer (CC) is right hemicolectomy (RH) in some Western countries while the principle of D3 lymphadenectomy in Japan recommends resecting approximately 10 cm from the tumor edge. Therefore, the optimal surgical approach for cecum cancer (CC) remains controversial. We conducted this retrospective study to explore the pattern of lymph node metastasis and better surgical procedures for CC.
METHODS: A total of 224 cecum cancer patients from January 1, 2014, to December 31, 2021, were retrospectively included in the final study. The pattern of lymph node metastasis (LNM) was investigated.
RESULTS: A total of 113 (50.4%, 113/224) patients had pathologically confirmed LNM. The most frequent metastatic site was no. 201 lymph node (46%, 103/224), while 20 (8.9%, 20/224) patients had LNM in no. 202 lymph node, and 8 (3.6%, 8/224) patients had LNM in no. 203 lymph node. Only 1 (0.4%, 1/224) patient had LNM in no. 221 lymph node, four (1.8, 4/224%) patients had LNM in no. 223 lymph node, and no patients had LNM in no. 222 lymph node. LNM in no. 223 lymph node was significantly associated with a poor prognosis. Multivariate analysis indicated that LNM in no. 223 lymph node (HR = 4.59, 95% CI 1.18-17.86, P = 0.028) was the only independent risk factor associated with worse disease-free survival (DFS).
CONCLUSIONS: The LNM in no. 223 lymph node for cecum cancer was rare. Therefore, standard right hemicolectomy excision is too extensive for most CC cases.

BACKGROUND: Variations of the vasculature at splenic flexure by left colic artery (LCA) and middle colic artery (MCA) remain ambiguous.
OBJECTIVE: This study aim to investigate the anatomical variations of the branches from LCA and MCA at splenic flexure area.
METHODS: Using ultra-thin CT images (0.5-mm thickness), we traced LCA and MCA till their merging site with paracolic marginal arteries through maximum intensity projection (MIP) reconstruction and computed tomography angiography (3D-CTA).
RESULTS: A total of 229 cases were retrospectively enrolled. LCA ascending branch approached upwards till the distal third of the transverse colon in 37.6%, reached the splenic flexure in 37.6%, and reached the lower descending colon in 23.1%, and absent in 1.7% of the cases. Areas supplied by MCA left branch and aMCA were 33.2%, 44.5% and 22.3% in the proximal, middle and distal third of transverse colon of the cases, respectively. The accessory MCA separately originated from the superior mesenteric artery was found in 17.9% of the cases. Mutual correlation was found that, when the LCA ascending branch supplied the distal transverse colon, MCA left branch tended to feed the proximal transverse colon; when the LCA ascending branch supplied the lower part of descending colon, MCA left branch was more likely to feed the distal third of transverse colon.
CONCLUSIONS: Vasculature at splenic flexure by LCA and MCA varied at specific pattern. This study could add more anatomical details for vessel management in surgeries for left-sided colon cancer.

UNASSIGNED: Due to the complexity of anatomical relationship between superior mesenteric artery (SMA) and left colic artery (LCA), there is no unified anatomical concept of \"Riolan\'s arch.\" There is no consensus as to tie off the inferior mesenteric artery (IMA) at its origin or just below the origin of the left colic artery during radical surgery of sigmoid colon and rectal cancers. The aim of the study is to investigate the anatomy of shortcut anastomotic branches (adjacent branches) of SMA at splenic flexure and to explore how the shortcut pathway (Riolan\'s arch) was formed, as the compensation of anastomotic branches between MCA and LCA under pathological conditions and the reconstruction and the mechanism of pathological Riolan\'s arch after high ligation of the inferior mesenteric artery.
UNASSIGNED: Between January 2018 and May 2020, patients with colorectal cancer who underwent CTA before surgery were enrolled in the study. The anatomy of shortcut anastomotic branch of SMA and LCA was investigated by volume rendering technique (VR) and maximum-intensity projection (MIP). GE\'s small vessel extraction technology (selected VR) was used to directly display these shortcut anastomotic branches on a map and to establish their three-dimensional anatomical classification. Then, we used the axonometric drawing to make the model more exact. Next, combining with some cases of pathological Riolan\'s arch and basing on hydrodynamic principle, we speculate the mechanism of collateral circulation. Finally, based on the retrospective study of high ligation cases and combined principles of fluid mechanics, we show how these shortcut anastomotic branches evolved into Riolan\'s arch.
UNASSIGNED: We report the classification of the ascending branch of LCA (which approaches the splenic flexure) and the left branch of MCA, display these shortcut anastomotic branches on a map, and establish their three-dimensional anatomical classification. We found that Riolan\'s arch is a shortcut pathway for the compensation of anastomotic branches, between MCA and LCA under pathological conditions, and that the formation mechanism of shortcut path accords with the principle of hydrodynamics.
UNASSIGNED: Our results show the mechanism of pathological Riolan\'s arch formation and provide new anatomic thinking for the battle between high and low ligation of IMA in colorectal cancer surgery.