Ligaments and Lymphatic Pathways in Gastric Adenocarcinoma

Gastric cancer is a leading cause of cancer-related deaths worldwide and is associated with an overall 5-year survival rate of less than 20%. The most common histologic subtype of gastric cancer is adenocarcinoma. Imaging techniques for evaluating gastric adenocarcinoma include endoscopic US, fluoroscopic upper gastrointestinal imaging, CT, PET/CT, and MRI. Hydrodynamic multiphasic contrast material-enhanced CT is the imaging modality of choice for preoperative clinical staging of regional, nodal, and metastatic involvement. Radiologic manifestations of gastric adenocarcinoma at double-contrast upper gastrointestinal imaging and CT include polyps, ulceration, indistensibility, wall thickening, and abnormal enhancement. There are multiple pathways of disease spread. These pathways include lymphatic dissemination; subperitoneal dissemination along the perigastric ligaments, mesentery, or omentum; direct invasion into adjacent organs; transperitoneal seeding; and hematogenous dissemination. The spread of disease is affected by the location of the tumor in the stomach, and the ligamentous and lymphatic anatomy. Key imaging features that affect clinical staging with use of the TNM classification system for gastric adenocarcinoma, as described in the eighth edition of the AJCC Cancer Staging Manual, are briefly discussed. Accurate radiologic assessment of gastric adenocarcinoma requires identification of perigastric ligament infiltration, regional and metastatic nodal disease, and direct and metastatic organ involvement, all of which directly affect tumor staging, treatment, and prognosis. (C) RSNA, 2019