Sentinel Lymph Node Biopsy in Thin Melanoma

The American Joint Committee on Cancer (AJCC) staging system (8th Edition) for thin melanomas (less than or equal to 1 mm):
- Includes both tumor thickness and ulceration as distinguishing features of a stage 1a and stage 1b melanoma
The American Society of Clinical Oncology (ASCO) and the Society for Surgical Oncology (SSO) jointly developed evidence-based recommendations for the use of SLN biopsy for patients with melanoma:
- The guidelines note that SLN biopsy is recommended for:
  - All patients with intermediate-thickness melanomas (between 1 and 4 mm):
    - Studies have shown that SLN biopsy is useful for identifying nodal metastases in these patients:
      - Who account for about one-third of all melanoma cases
    - SLN biopsy detects cancer in the sentinel nodes in about:
      - 18% to 26% of patients
  - The majority of melanomas are thin (1 mm thick) and usually can be cured simply by wide local excision of the primary tumor:
    - The incidence of tumor-positive SLN biopsy among patients with thin melanomas is approximately 5%
    - Although SLN biopsy is not necessary in most cases:
      - The guideline recommendations note that it should be discussed and considered for selected patients with:
        
        Thin melanomas (0.8mm to 1mm)
        
        Those with melanomas < 0.8mm and possess high-risk factors:
        
        Such as:
        
        Ulceration
        
        A mitotic rate of 1/ mm2
Wong et al:
- Evaluated the results of SLN biopsy in 223 patients with thin melanomas and found nodal metastasis to be uncommon among patients with:
  - Melanomas less than 0.75 mm thick
  - Less than Clark level IV
References:
- Wong SL, Faries MB, Kennedy EB, et al. Sentinel lymph node biopsy and Management of Regional Lymph Nodes in Melanoma: American Society of Clinical Oncology and Society of Surgical Oncology Clinical Practice Guideline Update. J Clin Oncol. 2018;36:399-413.
- Wong SL, Brady MS, Busam KJ, Coit DG. Results of sentinel lymph node biopsy in patients with thin melanoma. Ann Surg Oncol.;2006;13:302-309.