Diagnostic Approach for Male Patient with Gastric Symptoms and 10 kg Weight Loss
Proceed directly to upper endoscopy with biopsy as the definitive diagnostic test, followed by contrast-enhanced CT chest/abdomen/pelvis for staging if malignancy is confirmed. Tumor markers have no established role in the initial diagnosis of gastric cancer and should not be ordered 1.
Why Tumor Markers Are Not Recommended
- No tumor markers are recommended in current gastric cancer diagnostic guidelines 1
- The ESMO, CSCO, and ACR guidelines make no mention of tumor markers (CEA, CA 19-9, CA 72-4) for initial diagnosis of gastric cancer 1
- Histopathological examination via endoscopic biopsy is the gold standard and mandatory requirement before treatment initiation 1
The Correct Diagnostic Algorithm
Step 1: Upper Endoscopy with Biopsy (First-Line)
- This patient has alarm features (significant weight loss of 10 kg) which mandates immediate endoscopy 1
- Weight loss, dysphagia, dyspepsia, vomiting, and early satiety are common presenting features of gastric cancer 1
- Gastric cancer occurs twice as commonly in men, with peak incidence in the seventh decade 1
- Biopsy specimens must be reviewed by an experienced pathologist and reported according to WHO criteria 1
- The endoscopy should obtain tissue for histological classification and molecular biomarkers, specifically HER2 status 1
Step 2: Staging Investigations (Only After Confirmed Diagnosis)
- Routine blood tests to check for iron-deficiency anemia and assess hepatic/renal function 1
- Contrast-enhanced CT of thorax, abdomen, and pelvis is the primary staging modality 1
- The CT must use IV contrast with neutral oral contrast (500 mL water) to properly distend the stomach 1
- Plain CT scans without contrast are inadequate and not recommended 1
Step 3: Additional Staging for Confirmed Gastric Cancer
- Endoscopic ultrasound (EUS) for accurate T and N staging, with sensitivity of 0.86 and specificity of 0.90 for distinguishing T1/2 from T3/4 tumors 1
- EUS determines proximal and distal tumor extent but is less useful for antral tumors 1
- Diagnostic laparoscopy with peritoneal washings is recommended for all stage IB-III gastric cancers to detect occult peritoneal metastases 1
- PET imaging may improve detection of lymph node/metastatic disease but can be uninformative in mucinous tumors 1
Critical Clinical Context
Why Not Start with CT?
- While CT can suggest gastric cancer through nodular/irregular wall thickening, soft tissue attenuation, or masses, it cannot provide the tissue diagnosis required before treatment 1
- CT excels at detecting complications (perforation, obstruction, metastases) rather than making primary mucosal diagnoses 2, 3
- Endoscopy provides both diagnosis and therapeutic capability 2, 3, 4
The Problem with Relying on Symptoms Alone
- High-risk symptoms predict gastric cancer (OR 1.8) but do not reliably predict precursor lesions 5
- Alarm symptoms like weight loss and dysphagia are independently related to survival and suggest advanced disease 6
- Only 28% of patients with suspected gastric cancer based on symptoms actually have the disease 7
- Persistent vomiting (OR 3.68) is an independent predictor of gastric cancer 7
Common Pitfalls to Avoid
- Do not order tumor markers as part of the initial diagnostic workup - they have no validated role 1
- Do not perform CT before endoscopy in a patient with alarm symptoms - tissue diagnosis is mandatory and endoscopy should not be delayed 1, 4
- Do not use plain CT or CT without neutral oral contrast - this reduces sensitivity for gastric pathology 1
- Do not skip laparoscopy in potentially operable stage IB-III disease - it detects occult peritoneal metastases that change management 1