What tests are used to diagnose pancreatic cancer?

Diagnostic Tests for Pancreatic Cancer

The initial evaluation for suspected pancreatic cancer should begin with abdominal ultrasound, followed by contrast-enhanced multi-detector CT scan using a pancreatic protocol, and supplemented with EUS for tissue acquisition when necessary. 1

Initial Diagnostic Approach

First-Line Imaging

• Abdominal ultrasound: Should be performed first as it is widely available, non-invasive, and can detect pancreatic masses, bile duct dilation, and liver metastases 1
• Pancreatic protocol CT scan: The primary diagnostic modality for pancreatic cancer 1
  • Requires triphasic imaging (arterial, late arterial, and venous phases)
  • Should include thin slices using multidetector CT
  • Should cover chest, abdomen, and pelvis to evaluate for metastatic disease
  • Should be performed within 4 weeks before starting therapy 1

Second-Line Imaging

• MRI with MRCP: Indicated when:
  • CT is inconclusive (e.g., isoattenuating tumors)
  • CT is contraindicated
  • Small liver metastases are suspected 1, 2
• Endoscopic ultrasound (EUS): Particularly valuable for:
  • Small lesions (<2-3 cm)
  • Tissue acquisition via fine needle aspiration (FNA)
  • Evaluation of vascular involvement and lymph nodes 1, 2

Tissue Diagnosis

• EUS-guided FNA/biopsy: Preferred method for tissue acquisition due to:

  • Higher safety profile
  • Lower risk of peritoneal seeding compared to percutaneous approaches
  • Additional staging benefits during the procedure 2

• When tissue diagnosis is mandatory:

  • Unresectable disease
  • Before neoadjuvant therapy
  • When imaging results are ambiguous 1, 2

• When tissue diagnosis can be omitted:

  • Patients undergoing surgery with curative intent with clearly resectable disease
  • Failure to obtain histological confirmation should not delay appropriate surgical treatment in highly suspicious cases 1

Biomarkers and Laboratory Tests

• CA 19-9: Most clinically useful biomarker for pancreatic cancer

  • Sensitivity: 79-81%, Specificity: 80-90% 2
  • Limitations:
    • False negatives in Lewis-negative individuals (5-10% of population)
    • False positives with biliary obstruction, chronic pancreatitis, and other GI cancers
  • Should be measured after biliary decompression to avoid false positives 2

• Essential laboratory tests:

  • Liver function tests (bilirubin, AST, ALT, alkaline phosphatase)
  • Fasting glucose or HbA1c (new-onset diabetes may be an early sign) 2, 1

Special Considerations

High-Risk Individuals

• Individuals with family history of pancreatic cancer or genetic syndromes should be referred to specialist centers 1
• Annual EUS and/or pancreatic MRI are preferred for surveillance in high-risk individuals 1
• Screening should begin at age 50 or 10 years earlier than the youngest affected relative 1

Common Pitfalls to Avoid

1. Relying on PET-CT for initial diagnosis: Not routinely recommended due to overlap with findings in autoimmune and chronic pancreatitis 1, 2

2. Performing ERCP as a diagnostic tool: ERCP should be limited to therapeutic interventions for biliary obstruction, not for diagnosis 1

3. Preoperative biliary stenting: Should only be performed if surgery cannot be done expeditiously, as it increases risk of complications 1

4. Transperitoneal biopsy techniques: Should be avoided in potentially resectable tumors due to risk of tumor seeding 1

5. Dismissing pancreatic cancer in patients with negative imaging but high clinical suspicion: Consider EUS if initial imaging is negative 2

Clinical Warning Signs

• New-onset diabetes without predisposing factors in patients over 50 years
• Unexplained episode of acute pancreatitis
• Persistent back pain, marked weight loss, abdominal mass
• Painless jaundice (head tumors) 1

By following this systematic diagnostic approach, clinicians can improve the timely and accurate diagnosis of pancreatic cancer, which is essential for improving outcomes in this highly lethal disease.