What are the typical blood work findings in patients with melanoma?

Typical Blood Work Findings in Patients with Melanoma

Elevated lactate dehydrogenase (LDH) is the most significant blood work finding in melanoma patients, particularly in those with stage IV disease, where it serves as an independent predictor of poor outcome. 1

Key Blood Work Findings by Stage

Stage I-III Melanoma

• Routine blood work is generally not recommended for early-stage melanoma (stages I-II) as it has low sensitivity and specificity 2
• For stage III melanoma:
  • Blood tests are typically performed at physician's discretion
  • No specific blood marker has proven consistently valuable for routine screening
  • LDH may be checked but is not routinely recommended for surveillance 1

Stage IV Melanoma

• LDH is the most important blood marker:

  • Elevated LDH is incorporated into the AJCC staging system for stage IV melanoma 1
  • High LDH levels correlate with poor prognosis (HR=1.97,95% CI 1.62-2.40) 3
  • LDH isoenzymes 3 and 4 are significantly increased while isoenzymes 1 and 2 are decreased in advanced melanoma 4
  • The NCCN recommends obtaining serum LDH at diagnosis of stage IV disease 1

• S100B protein:

  • Rising serum S100B has higher specificity for disease progression than LDH 1
  • S100B is an independent prognostic factor in melanoma patients with distant metastasis 5
  • Patients with both normal LDH and S100B values have better prognosis after complete metastasectomy (5-year survival of 37.2%) 5

Clinical Significance of Blood Work Findings

1. Prognostic Value:

   • Elevated LDH correlates with reduced progression-free survival in patients receiving immunotherapy (5 months vs. not reached in patients with normal LDH) 6
   • High LDH is associated with liver metastases and poorer outcomes 6

2. Disease Monitoring:

   • Serial LDH measurements help monitor disease progression and treatment efficacy 2
   • However, LDH levels alone may not provide real-time information about disease status and treatment response 7

3. Treatment Decision-Making:

   • Patients should not be treated based solely on elevated LDH, as it lacks specificity 2
   • LDH levels should be interpreted in context with other clinical and laboratory findings 2

Important Caveats and Pitfalls

• Low Specificity: LDH elevation can occur in many conditions beyond melanoma, including other malignancies, infections, and tissue damage 2
• Limited Utility in Early Disease: Testing of serum LDH is not recommended at baseline or for surveillance in patients with stage I-III melanoma 2
• Interpretation Challenges: LDH results must be interpreted in the context of the overall clinical picture 2
• Emerging Alternatives: Circulating cell-free microRNAs (particularly miR-615-3p) may be more efficient than LDH in detecting disease progression during checkpoint inhibitor immunotherapy 7

Recommended Approach to Blood Work in Melanoma

1. Stage I-II: Routine blood tests not recommended unless specific symptoms warrant investigation 1
2. Stage III: Blood work at physician's discretion; consider LDH if clinically indicated 1
3. Stage IV:
   • Obtain serum LDH at diagnosis 1
   • Consider S100B as a complementary marker 1, 5
   • Monitor LDH levels during treatment to assess response 2
   • Consider additional blood work based on clinical presentation and symptoms 1

In conclusion, while LDH remains the most established blood marker in melanoma, its greatest utility is in advanced disease. For early-stage melanoma, routine blood work has limited value, and clinical examination remains the cornerstone of follow-up.