What blood tests are useful for detecting melanoma?

Blood Tests for Melanoma Detection

Blood tests are not recommended for initial detection or screening of melanoma, as diagnosis relies on clinical examination and biopsy; however, serum S-100B protein is the most accurate blood marker for monitoring disease progression and detecting metastases in patients with established melanoma. 1

Primary Detection: Blood Tests Are Not Used

• No blood test can detect early melanoma or serve as a screening tool 1
• Melanoma diagnosis requires visual skin examination and histopathologic confirmation through biopsy 1
• There is no consensus supporting routine blood testing for melanoma detection in asymptomatic individuals 1

Blood Tests for Follow-Up and Monitoring (Not Detection)

S-100B Protein: The Most Accurate Marker

• Serum S-100B has higher specificity for disease progression than LDH and is the most accurate blood test for melanoma follow-up, if any blood test is used at all 1
• S-100B demonstrates 86% sensitivity for detecting newly occurred metastases with 91% specificity 2
• S-100B is superior to LDH in identifying early distant metastasis (53.8% vs 23.1%, p=0.008) 3
• Using a cutoff of 0.20 μg/L, S-100B achieves 93% specificity with 68% sensitivity for active disease 4
• S-100B is an independent predictor of survival in stage IV disease 4

Lactate Dehydrogenase (LDH)

• LDH has lower specificity than S-100B for disease progression 1
• LDH shows only 48% sensitivity for newly occurred metastases, though specificity is high at 98% 2
• LDH levels correlate with number of metastatic sites but are less reliable than S-100B 4

Other Markers (Research Context Only)

• Melanoma Inhibiting Activity (MIA) combined with S-100B shows better diagnostic sensitivity than either marker alone, though this remains investigational 5
• The combination of S-100B plus MIA achieved 80% sensitivity for metastases 2
• Indoleamine 2,3-dioxygenase (IDO) shows promise as a prognostic marker, with levels significantly elevated in stages IB-IV at diagnosis 6

Critical Limitations and Caveats

• Neither S-100B nor LDH can detect loco-regional metastases with low tumor burden 3
• Blood markers are not indicators of in-transit metastases 3
• Clinically apparent lymph nodes are rarely detected by elevated S-100B (29.4%) or LDH (11.8%) alone 3
• Routine blood testing is not recommended for patients with thin primary melanomas who have minimal relapse risk 1
• Blood tests may only be considered in high-risk patients (thick primary tumors, post-metastasis treatment) as part of comprehensive monitoring 1

Guideline Recommendations

• ESMO guidelines state there is no consensus on the utility of blood tests for patients with resected melanoma 1
• If blood testing is performed at all, S-100B is preferred over LDH with a low level of evidence (Level IV, Grade D) 1
• Follow-up relies primarily on clinical skin and lymph node examinations, not blood tests 1
• Patient self-examination of skin and lymph nodes monthly is more emphasized than any blood testing 1, 7, 8