A 58-year-old Indian man presents with progressive dysphagia, early satiety, and weight loss of 8 kg over 3 months. Upper GI endoscopy reveals a large ulcerated lesion in the gastric antrum with rolled edges. Biopsy from the lesion shows adenocarcinoma. What is the most appropriate investigation to determine the depth of tumor invasion and locoregional lymph node involvement before staging?

Question

Accepted Answer

C. Endoscopic ultrasound (EUS) with fine-needle aspiration. ## Investigation of Choice for Locoregional Staging in Gastric Carcinoma

### Why Endoscopic Ultrasound (EUS) is Optimal

**Key Point:** EUS is the gold standard for assessing T-stage (depth of tumor invasion) and N-stage (regional lymph node involvement) in gastric cancer. It provides superior resolution of the gastric wall layers and perigastric lymph nodes compared to cross-sectional imaging.

**High-Yield:** EUS can:
- Differentiate between T1a (mucosa), T1b (submucosa), T2 (muscularis propria), T3 (subserosa), and T4 (serosa/adjacent structures)
- Identify regional lymph nodes (N1, N2) with >90% accuracy for nodes >3 mm
- Guide fine-needle aspiration (FNA) for cytological confirmation of involved nodes
- Assess resectability in early-stage disease

### Role of Other Investigations

| Investigation | Role in Gastric Cancer | Limitation |
|---|---|---|
| **CT chest/abdomen** | Detects distant metastases (M-stage), assesses peritoneal involvement | Poor resolution for T-stage and small regional nodes (<1 cm) |
| **PET-CT** | Identifies distant metastases and FDG-avid nodes | Low sensitivity for small primary tumors and T-staging |
| **Diagnostic laparoscopy** | Detects peritoneal/liver metastases missed on imaging | Invasive; not first-line for locoregional staging |

**Clinical Pearl:** In this patient with histologically confirmed adenocarcinoma, EUS should be performed before CT staging to guide treatment decisions (surgery vs. neoadjuvant chemotherapy).

**Mnemonic — EUS in Gastric Cancer (T-N-E):**
- **T** = Tumor depth (T-stage)
- **N** = Node involvement (N-stage)
- **E** = Endoscopic approach (no radiation, real-time assessment)

**Warning:** EUS is operator-dependent and may be limited by gastric stenosis or inability to pass the scope; in such cases, CT or MRI becomes the alternative.

Answer

A. Positron emission tomography (PET)-CT

Answer

B. Contrast-enhanced CT chest and abdomen

Answer

D. Diagnostic laparoscopy

Explanation

Investigation of Choice for Locoregional Staging in Gastric Carcinoma

Why Endoscopic Ultrasound (EUS) is Optimal

Role of Other Investigations

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Investigation	Role in Gastric Cancer	Limitation
CT chest/abdomen	Detects distant metastases (M-stage), assesses peritoneal involvement	Poor resolution for T-stage and small regional nodes (<1 cm)
PET-CT	Identifies distant metastases and FDG-avid nodes	Low sensitivity for small primary tumors and T-staging
Diagnostic laparoscopy	Detects peritoneal/liver metastases missed on imaging	Invasive; not first-line for locoregional staging