From the Guidelines
Gastric cancer diagnosis primarily relies on endoscopic ultrasound (EUS) findings, including gastric wall thickening, loss of the normal five-layered wall structure, and irregular or nodular mucosal patterns, as evidenced by the most recent guidelines from the Chinese Society of Clinical Oncology (CSO) in 2019 1. Key ultrasound findings in gastric cancer include:
- Gastric wall thickening greater than 4mm
- Loss of the normal five-layered wall structure
- Irregular or nodular mucosal patterns
- Hypoechoic masses within the gastric wall
- Disruption of wall layers with transmural extension
- Regional lymphadenopathy, particularly in the perigastric, celiac, and porta hepatis regions Advanced cases may show evidence of invasion into adjacent structures such as the liver, pancreas, or omentum. EUS is superior to conventional ultrasound for gastric cancer evaluation, offering better visualization of wall layers and more accurate T-staging with a depth resolution of 0.1mm, as supported by the NCCN clinical practice guidelines in oncology in 2016 1. The use of EUS is recommended as the preferred cT staging modality for the clinical evaluation of the depth of tumor invasion, with a sensitivity and specificity of 0.86 and 0.90, respectively, in distinguishing between T1/2 and T3/4 cancers 1. While ultrasound findings are suggestive, definitive diagnosis requires endoscopic biopsy confirmation. Ultrasound's main limitations include operator dependence, interference from bowel gas, and difficulty visualizing certain gastric regions, particularly the fundus. The American Gastroenterological Association Institute technical review on the management of gastric subepithelial masses in 2006 also highlights the importance of EUS-guided FNA in confirming the presence of malignancy in lymph nodes or organs adjacent to the gastrointestinal tract 1.
From the Research
Gastric Cancer Ultrasound Findings
- The gastric wall is typically visualized as five distinct layers on ultrasound: a first, inner hyperechoic layer; a second, hypoechoic layer; a third, middle hyperechoic layer; a fourth, hypoechoic layer; and a final, outer hyperechoic layer 2.
- The inner hyperechoic layer is constant in thickness, measuring 1 mm, and is due to echoes arising from the interface between fluid in the gastric lumen and the mucosal surface 2.
- The underlying hypoechoic layer is caused by the mucosa itself and can be obliterated or thickened depending on the condition of the mucosa 2.
Endoscopic Ultrasound in Gastric Cancer
- Endoscopic ultrasound (EUS) plays a key role in the diagnosis and staging of gastric cancer, allowing for in-depth cancer staging by detailing tumor size, depth of invasion in the gastric wall, presence of metastatic lymphadenopathy, and detection of liver metastases 3.
- EUS can distinguish the different wall layers of the gastrointestinal tract as well as assess regional lymph nodes, and samples of suspicious lesions or lymph nodes can be obtained by means of EUS-guided fine-needle aspiration (EUS-FNA) 4.
- EUS can also help distinguish among a variety of subepithelial gastric mass lesions, many of which are neoplastic, and guide decision management in terms of appropriateness for endoscopic or surgical resection and overall management strategy for patients 3.
Ultrasound Findings in Gastric Cancer Staging
- EUS can assess the depth of invasion in the gastric wall and the presence of metastatic lymphadenopathy, which are crucial for determining the stage of gastric cancer 5, 4.
- EUS can also detect liver metastases, which is important for determining the overall management strategy for patients with gastric cancer 3.
- The use of EUS tools such as elastography, Doppler, and contrast administration can improve diagnosis, mainly in case of malignant lymph node evaluation 5.