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.

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