Can tumor markers (Carcinoembryonic Antigen (CEA), Cancer Antigen 19-9 (CA 19-9), Cancer Antigen 72-4 (CA 72-4)) be used for initial diagnosis of gastric cancer in a male patient with gastric symptoms and significant weight loss?

Tumor Markers for Initial Diagnosis of Gastric Cancer

Tumor markers including CEA, CA 19-9, and CA 72-4 should NOT be used for screening or initial diagnosis of gastric cancer in symptomatic patients; instead, proceed directly to upper endoscopy with biopsy, which is the gold standard diagnostic test.

Why Tumor Markers Are Inadequate for Initial Diagnosis

The major international guidelines explicitly exclude tumor markers from the diagnostic workup for gastric cancer:

• ESMO guidelines specify that initial investigations include physical examination, blood count, and contrast-enhanced CT scan, but do NOT recommend tumor markers for diagnosis 1
• The diagnostic standard requires gastroscopic or surgical biopsy reviewed by an experienced pathologist 1
• Tumor markers lack sufficient sensitivity and specificity for detecting gastric cancer, particularly early-stage disease 2, 3

Evidence Against Using Tumor Markers for Diagnosis

Research consistently demonstrates the limitations of these markers:

• CEA, CA 19-9, and CA 72-4 should not be used for screening and early diagnosis in gastric cancer due to inadequate sensitivity and specificity 2
• Individual sensitivities are poor: CEA (22.69%), CA 19-9 (18.98%), and CA 72-4 (22.69%) 4
• Even when combined, the sensitivity only reaches 44.91-75%, which is insufficient for diagnostic purposes 4, 5
• These markers are more useful for detecting late-stage disease rather than early gastric cancer 2

The Correct Diagnostic Approach for Your Patient

For a male patient with gastric symptoms and significant weight loss:

1. Proceed immediately to upper endoscopy with multiple biopsies 1

   • This is the reference standard for diagnosis 6
   • Multiple four-quadrant biopsies increase diagnostic accuracy 1
   • Obtain tissue for histological classification and molecular biomarkers (particularly HER2 status) 1, 6

2. Order routine blood tests focusing on iron-deficiency anemia 1, 7

   • Iron-deficiency anemia may be the only presenting sign of gastric cancer 7, 6
   • This is more clinically relevant than tumor markers for initial evaluation

3. Consider contrast-enhanced CT scan of thorax, abdomen, and pelvis 1, 6

   • This is for staging purposes once diagnosis is confirmed, not for initial diagnosis

When Tumor Markers May Have Limited Utility

Tumor markers have a role AFTER diagnosis is established:

• Prognostic assessment: Elevated pretreatment levels of CA 72-4 and CA 19-9 may indicate worse prognosis in metastatic disease 5
• Monitoring during treatment: Combined measurement of CEA, CA 19-9, and CA 72-4 in shorter time intervals can help monitor treatment response 2
• Detection of recurrence: May be useful in follow-up after curative treatment 2

Critical Pitfalls to Avoid

• Never delay endoscopy to wait for tumor marker results in a symptomatic patient with alarm features (weight loss, dyspepsia, early satiety) 1, 7
• Do not use negative tumor markers to rule out gastric cancer - their poor sensitivity means many patients with cancer will have normal values 2, 3
• Failure to perform endoscopy based on reassuring tumor markers is a major diagnostic error that leads to delayed diagnosis 1

Additional Risk Factors to Document

Your male patient has several concerning features that warrant urgent investigation:

• Male gender increases gastric cancer risk approximately 2-fold 1, 7
• Weight loss is a common presenting feature occurring in 30-87% of gastric cancer patients 1
• Consider testing for H. pylori infection, which is a major risk factor 1, 7