We focused on the embryology and topographic anatomy of the infrapyloric lymph region, which is frequently involved in node metastases but technically complicated for dissection in gastric cancer surgery. Gastrointestinal organs possess their own mesenteries composed of double layers of peritoneum that enclose the intermediate adipose layer providing pathways for vessels, nerves, and lymphatic channels. The frontal layer of the mesoduodenum, in which no. 6 infrapyloric nodes lie, directly faces the pancreas and during gestation is overlain by the greater omentum and transverse mesocolon through the membranous connective tissue called the fusion fascia. Therefore, we performed no. 6 node dissection using the following process: (1) we traced out the mesoduodenum by detachment of the greater omentum and transverse mesocolon; (2) we transected the fusion fascia and (3) removed the adipose layer on the anterior face of the pancreas with its included lymph nodes together with the right gastroepiploic and infrapyloric vessels. The described technique is feasible and in keeping with the anatomical logic for oncologically reliable dissection of no. 6 infrapyloric nodes.

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The prediction of anatomical structures within the surgical field by artificial intelligence (AI) is expected to support surgeons’ experience and cognitive skills. We aimed to develop a deep-learning model to automatically segment loose connective tissue fibers (LCTFs) that define a safe dissection plane. The annotation was performed on video frames capturing a robot-assisted gastrectomy performed by trained surgeons. A deep-learning model based on U-net was developed to output segmentation results. Twenty randomly sampled frames were provided to evaluate model performance by comparing Recall and F1/Dice scores with a ground truth and with a two-item questionnaire on sensitivity and misrecognition that was completed by 20 surgeons. The model produced high Recall scores (mean 0.606, maximum 0.861). Mean F1/Dice scores reached 0.549 (range 0.335–0.691), showing acceptable spatial overlap of the objects. Surgeon evaluators gave a mean sensitivity score of 3.52 (with 88.0% assigning the highest score of 4; range 2.45–3.95). The mean misrecognition score was a low 0.14 (range 0–0.7), indicating very few acknowledged over-detection failures. Thus, AI can be trained to predict fine, difficult-to-discern anatomical structures at a level convincing to expert surgeons. This technology may help reduce adverse events by determining safe dissection planes.

This study investigated the incidence of gastric cancer metastasis to the lymph nodes along the infrapyloric artery (IPA), namely no. 6i, by reviewing our medical records of 348 patients who underwent complete no. 6 dissection. Metastasis to these nodes was observed in 11 (3.2 %) patients. In these patients, one huge tumor was located in the middle third and ten including two early tumors were located in the lower third; the metastasis rate in early lower-third tumors was 2.1 % and reached 19.5 % in advanced tumors. In contrast, no early middle-third gastric cancers had no. 6i metastasis. The median diameter of 6i-positive tumors was 62 (range 18-115) mm, and the distance from the distal tumor border to the pyloric ring was no more than 44 mm. Lymphadenectomy along the IPA is important for treating gastric cancer invading the antrum, but may be dispensable when performing pyloruspreserving gastrectomy for early middle-third cancer.

Gastrointestinal cancer surgery aims at en bloc removal of the primary tumor with its lymphatic drainage by excising organ‐specific mesentery as an “intact package”. This concept was advocated in colorectal cancer surgery as total mesorectal excision (TME) or complete mesocolic excision (CME) procedures, but is not directly applicable to stomach cancer as a result of the morphological complexities of the gastric mesentery. In this review, we discuss the unique anatomical features of the mesogastrium by introducing its embryology, disclose its similarity to the mesosigmoid, and then propose a theoretical concept to mesentery‐based D2 gastrectomy, namely systematic mesogastric excision, which can universalize the operative strategy of stomach cancer with that of TME and CME colorectal counterparts.