Early and advanced cancer
In clinical practice, two main forms are distinguished:
- Early gastric cancer is confined to the mucosal and submucosal layers. The gold standard for diagnosis here is endoscopy with multiple biopsies. On multislice computed tomography (MSCT), such lesions are difficult to detect, but modern techniques (virtual gastroscopy, 3D reconstructions) allow the identification of focal thickening and intense contrast enhancement.
- Advanced cancer invades the muscular layer (muscularis propria) and extends deeper. Macroscopically, it can be polypoid, ulcerated, or infiltrative. On fluoroscopy, the edges of the tumor may form a "shelf", indicating a mucosal origin.
Infiltrative forms deserve special attention. Scirrhous (desmoplastic) tumors cause total wall thickening with smoothing of the mucosal folds. This phenomenon is described by the term linitis plastica (linitis plastica) — the stomach turns into a rigid, narrowed tube resembling a "leather bottle".
TNM staging system
The TNM classification is used for staging. An important rule for esophagogastric junction tumors: if the epicenter of the lesion is located no more than 2 cm proximally in the stomach, it is staged as esophageal cancer. If the epicenter is located further than 2 cm, it is staged as gastric cancer.
Depth of invasion (T):
- T1: invasion into the lamina propria or muscularis mucosae (T1a), or into the submucosa (T1b).
- T2: invasion into the muscular layer (muscularis propria).
- T3: invasion into the subserosal connective tissue.
- T4: tumor extension to the visceral peritoneum (T4a) or direct invasion into adjacent structures, such as the liver or pancreas (T4b).
Lymph node involvement (N): Evaluated exclusively based on the number of metastatic nodes. N1 — 1–2 nodes, N2 — 3–6 nodes, N3 — 7 or more. The threshold size criterion for a suspicious lymph node on CT/MRI is usually considered to be 6–8 mm along the short axis.
Diagnostic imaging challenges
MSCT and endoscopic ultrasound are complementary methods for locoregional staging. However, imaging methods have objective limitations:
- Differentiation of T2 and T3 is extremely difficult because the subserosa and serosa are not visualized as separate anatomical structures.
- Assessment of organ invasion (T4b) cannot be based solely on the absence of a fat plane between the stomach and an adjacent organ (it may disappear due to cachexia). It is necessary to detect changes in X-ray density or MR signal in the tissue of the adjacent organ.
- 18F-FDG PET-CT is excellent for detecting peritoneal metastases and N3 stage nodes, but has blind spots: signet-ring cell and mucinous adenocarcinomas may not take up the radiopharmaceutical.
Differential diagnosis with lymphoma
The stomach is the most frequent site of extranodal lymphomas (typically non-Hodgkin B-cell lymphomas). Radiologically, lymphoma has no specific pattern and can mimic carcinoma.
The following signs favor lymphoma on a CT scan:
- Perigastric fat planes are preserved even if the tumor has reached a large size.
- The gastric wall remains pliable despite massive infiltration (unlike scirrhous cancer, lymphomatous linitis plastica occurs without fibrosis).
- The gastric lumen is preserved, and gastric outlet obstruction is rare.
- Massive lymphadenopathy is observed; node conglomerates can extend below the level of the renal hila.
Briefly: answers to topical questions
Which anatomical groups of lymph nodes are considered regional in gastric cancer?
Regional lymph nodes in gastric cancer include the following anatomical groups:
- Perigastric — along the greater and lesser curvature.
- Paracardial — right and left (cardioesophageal).
- Pyloric — suprapyloric and infrapyloric.
- Arterial — along the left gastric, common hepatic, celiac arteries (celiac artery), and along the splenic artery.
- Hepatoduodenal — along the proper hepatic artery, including the portal vein.
- Splenic hilum nodes.
First-order regional nodes also include the gastric lymph nodes (nodi lymphoidei gastrici), and second-order nodes include the celiac lymph nodes (nodi lymphoidei coeliaci).
What specific radiological signs of a malignant gastric ulcer are seen on barium contrast studies?
A specifically described feature in literature of a "malignant ulcer" (malignant ulcer) is an ulcer within a mass lesion of the stomach, usually a carcinoma, less commonly a lymphoma. In advanced gastric cancer, large polypoid lesions may show ulceration; their edges may form a "shelf" (shelf) and an acute angle with the gastric wall. Regardless of radiological or CT signs, a malignant ulcer always requires an endoscopic biopsy.
What are the macroscopic types of advanced gastric cancer according to the Borrmann classification?
According to the Borrmann classification, there are 4 macroscopic types of advanced gastric cancer:
- Type 1 (polypoid/fungating) — exophytic growth as a nodule, the tumor is clearly demarcated, ulceration is absent or minimal.
- Type 2 (ulcerated with distinct margins/disciform) — a deep ulcer in the center with raised, roll-like borders, clear margins, without macroscopic infiltration.
- Type 3 (ulcerative-infiltrative) — ulceration without clear margins, smoothed edges, the tumor infiltrates deeper layers and the surrounding mucosa.
- Type 4 (diffuse) — characterized by a diffuse growth pattern and wall infiltration.
What specific pathways of distant metastasis of gastric cancer exist (eponymous metastases)?
Specific distant (retrograde and implanting) metastases of gastric cancer include the following eponymous forms:
- Virchow's metastasis — involvement of the left supraclavicular lymph node (between the heads of the sternocleidomastoid muscle).
- Krukenberg's metastasis (Krukenberg tumor) — metastatic involvement of the ovaries.
- Schnitzler's metastasis (Schnitzler's tumor) — dissemination into the perirectal tissue and the peritoneum of the rectouterine pouch (Douglas pouch).
In addition, there is a specific metastasis to the umbilicus, spreading along the course of the round ligament of the liver.
Depth of invasion (T): T1 — mucosa and submucosa (internal), T2 — muscularis, T3 — subserosal tissue, T4 — peritoneum and adjacent organs (extension outside).
Class and exam questions
How are cardiac tumors classified according to TNM?
If the tumor epicenter is within 2 cm of the esophagogastric junction, it is esophageal cancer. If it is more than 2 cm toward the stomach or the junction is not involved, it is gastric cancer.
Does PET-CT always show gastric cancer?
No, some histological subtypes, such as signet-ring cell and poorly differentiated adenocarcinomas, may not take up FDG.
What is a malignant gastric ulcer?
This is an ulcer that has formed inside a mass lesion (carcinoma or lymphoma). Regardless of its imaging appearance, an endoscopic biopsy is always required.
What else to study on this topic
- Topography of regional and non-regional lymph nodes of the stomach
- Pathogenesis of MALT lymphoma and the role of Helicobacter pylori infection
- Krukenberg tumor and features of gastric cancer metastasis
- The role of virtual gastroscopy and 3D reconstructions in the diagnosis of early cancer
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