Gastric Cancer Staging: Is It Time for Magnetic Resonance Imaging?

Abstract

Gastric cancer (GC) is a common cancer worldwide. Its incidence and mortality vary depending on geographic area, with the highest rates in Asian countries, particularly in China, Japan, and South Korea. Accurate imaging staging has become crucial for the application of various treatment strategies, especially for curative treatments in early stages. Unfortunately, most GCs are still diagnosed at an advanced stage, with the peritoneum (61–80%), distant lymph nodes (44–50%), and liver (26–38%) as the most common metastatic locations. Metastatic disease is limited to the peritoneum in 58% of cases; in nonperitoneal distant metastases, the most involved GC metastasization site is the liver (82%). The eighth edition of the tumor-node-metastasis staging system is the most commonly used system for determining GC prognosis. Endoscopic ultrasonography, computed tomography, and 18-fluorideoxyglucose positron emission tomography are historically the most accurate imaging techniques for GC staging. However, studies have recently shown renewed interest in magnetic resonance imaging (MRI) as a useful tool in GC staging, especially for distant metastasis assessment. The technical improvement of diffusion-weighted imaging and the increasing use of hepatobiliary contrast agents have been shown to increase the diagnostic performance of MRI, particularly for detecting peritoneal and liver metastasis. However, no principal oncological guidelines have included the use of MRI as a first-line technique for distant metastasis evaluation during the GC staging process, such as the National Comprehensive Cancer Network Guidelines. This review analyzed the role of the principal imaging techniques in GC diagnosis and staging, focusing on the potential role of MRI, especially for assessing peritoneal and liver metastases.

Tumor-Associated Macrophages and Inflammatory Microenvironment in Gastric Cancer: Novel Translational Implications

“…Among the biological mechanisms involved in anticancer immunity, T-cell adaptive immunity has been suggested to play a key role in this setting [ 56 ]; more specifically, CD8+ T cells, CD4+ T helper cells, FOXP3+ regulatory T cells, memory T cells, and NK cells can infiltrate the stromal tissue, thus modifying the host immune response against cancer cells [ 57 , 58 ]. Over the last decade, several reports have highlighted that the GC microenvironment could be associated with the infiltration of tumor lymphocytes [ 5 , 59 ]. TILs may cause potent anticancer responses, preventing tumor growth and eradicating cancer cells; moreover, TILs have been suggested to enhance inflammation through the secretion of chemokines, cytokines, and matrix metalloproteinases [ 60 , 61 ].…”

“…tissue, thus modifying the host immune response against cancer cells [57,58]. Over the last decade, several reports have highlighted that the GC microenvironment could be associated with the infiltration of tumor lymphocytes [5,59]. TILs may cause potent anticancer responses, preventing tumor growth and eradicating cancer cells; moreover, TILs have been suggested to enhance inflammation through the secretion of chemokines, cytokines, and matrix metalloproteinases [60,61].…”

“…Immunotherapy has drastically improved the treatment options for many solid tumors; in advanced GC, the combination of chemotherapy and immunotherapy seems the most promising approach, based on the results of the CheckMate 649 study presented at the last European Society of Medical Oncology (ESMO) 2020 virtual meeting [ 3 , 4 ]. Nevertheless, the prognosis of GC patients remains dismal at present, since more than half of the patients are diagnosed at an advanced and/or metastatic stage of the disease, with a median overall survival time of roughly 1 year [ 2 , 5 , 6 ].…”

Immune Landscape of Gastric Carcinoma Tumor Microenvironment Identifies a Peritoneal Relapse Relevant Immune Signature

“…The continuous technical improvements have shown that it can enhance high contrast resolution and characteristic soft-tissue of magnetic resonance imaging (MRI), especially the diagnostic value of small liver metastases (≤10mm) and peritoneal implantation (29)(30)(31). However, MRI is usually associated with higher costs, longer acquisition time and a lower robustness with no major oncology guidelines to recommend preoperative evaluation of GC (32)(33)(34)(35). In contrast, the predictive value of 18F FDG PET/CT was high in several metastasis from GC including peritoneal metastasis, however, its limited usability and high costs would only make PET an alternative imaging modality 36).…”

Controversies in EUS: Do we need miniprobes?

“…Sophisticated CT and magnetic resonance imaging or sentinel node mapping techniques[ 137 138 ] are being developed to high-resolution capacities at least as potent as the old conventional EUS. [ 139 140 ] However, none of them can capture micrometastases <5 mm. [ 141 ]…”