What lab tests are needed to check for melanoma markers and active tumors?

Laboratory Tests for Melanoma Markers and Active Tumors

For melanoma monitoring and detection of active tumors, serum S-100 protein is the most accurate blood test, while imaging studies are only recommended for high-risk patients or those with advanced disease. 1

Recommended Laboratory Tests

Blood Tests

• Serum S-100 protein: The most specific and accurate blood marker for melanoma progression and monitoring 1
• Lactate Dehydrogenase (LDH):
  • Mandatory for staging of metastatic disease (stage IV) 1
  • Elevated LDH is associated with worse survival outcomes in stage IV melanoma 2
  • Included in the AJCC staging system for melanoma 1

Optional/Supplementary Blood Tests

• Melanoma-Inhibiting Activity (MIA): May correlate with melanoma progression but less widely used 3
• Tyrosinase: Limited clinical utility as it shows inconsistent correlation with disease stage 4

Imaging Studies (Not Laboratory Tests)

• Not recommended for early-stage disease: Routine imaging is not recommended for patients with stage I-II melanoma 1
• For high-risk patients: Consider imaging only for:
  • Thick primary tumors
  • Following treatment of metastases
  • Stage IIB and higher 1

Testing Algorithm Based on Disease Stage

For Known Melanoma Patients:

1. Stage I-II (Localized disease):

   • No routine blood tests recommended 1
   • S-100 protein may be considered but has limited value in early stages 3

2. Stage III (Regional metastasis):

   • Serum S-100 protein monitoring 1
   • LDH measurement (though less sensitive than S-100) 1

3. Stage IV (Distant metastasis):

   • Mandatory LDH measurement (prognostic value) 1, 2
   • Regular S-100 protein monitoring 1
   • BRAF mutation testing (from tumor tissue, not blood) for treatment decisions 1

For Suspected Melanoma Recurrence:

• Serum S-100 protein is the most reliable marker for early detection of relapse 1, 3
• Rising S-100 levels may indicate tumor growth before clinical or radiological evidence 3

Important Caveats

• Limited screening value: No serum marker is suitable for screening or diagnosis of primary melanomas 3
• Interpretation context: Blood markers alone have limited specificity and must be interpreted in clinical context 2
• Serial measurements: More valuable than single readings for monitoring disease progression 2, 3
• False positives: S-100 can be elevated in other conditions (neurological disorders, trauma) 3
• Tumor burden dependency: Current markers only reflect existing tumor burden and cannot predict recurrence in tumor-free patients 3

Key Takeaway

For monitoring melanoma and detecting active tumors, serum S-100 protein offers the highest specificity among blood tests, with LDH being mandatory for staging in advanced disease. However, these tests should complement rather than replace clinical evaluation and appropriate imaging studies in high-risk patients.