Staging of Gastric Cancer: CT Patterns and Correlation with Pathologic Findings

Gastric adenocarcinoma is mostly locally advanced at diagnosis. An appropriate pretherapy clinical staging is essential, with assistance from contrast-enhanced CT. In primary staging, CT is the first option for tumor (T), nodal (N), and metastatic (M) staging. One of the most relevant radiologic challenges is to reach an accurate TNM staging and reduce the risk of under- or overstaging. The CT benefits for local staging are linked to an appropriate protocol, primarily based on fasting, gastric lumen distention, and administration of intravenous contrast material. It is necessary for radiologists to have a deep knowledge of the macroscopic and microscopic anatomy of the stomach to assess clinical T staging and be aware of limited CT accuracy in the differentiation between stages T1 and T2, and the mismatch between histologic and radiologic multilayer visualization. Regarding N and M staging, the relevance of CT has high variability. For N staging, standardized criteria have not been approved yet, and for M staging, the variability mostly is dependent on the localization of metastatic disease. In peritoneal involvement, laparoscopic examination currently is recommended in doubtful and high-risk patients. Upfront surgery is the first option only in stage Ia, macrosatellite instability patients, or cases of emergency. Perioperative chemotherapy currently is recommended for stage Ib or higher with microsatellite stability status. According to these therapeutic options, pretherapy clinical staging plays an important part for clinicians to manage patients properly.