Stratifying SLN incidence in intermediate thickness melanoma patients

Area of Science:

• Oncology
• Dermatology
• Surgical Pathology

Background:

• Current melanoma guidelines recommend sentinel lymph node biopsy (SLNB) for tumors 1 mm or thicker.
• Emerging data suggests that melanomas less than 1.5 mm may represent a low-risk group for positive SLNB.

Purpose of the Study:

• To identify predictors of positive sentinel lymph node biopsy (SLNB) in patients with intermediate thickness melanoma (1.01-4.00 mm).
• To stratify risk within this patient group to potentially refine treatment decisions.

Main Methods:

• Retrospective analysis of a multicenter database (Sentinel Lymph Node Working Group).
• Inclusion of 3460 patients with intermediate thickness melanoma who underwent SLNB.
• Assessment of univariate and multivariate factors associated with positive SLNB results.

Main Results:

• Overall, 17% of patients had a positive SLNB.
• Significant predictors for positive SLNB included younger age, tumor location on trunk/lower extremity, Breslow depth ≥2 mm, ulceration, and higher mitotic rate.
• Multivariate analysis confirmed age, tumor location, and Breslow depth as key predictors.
• Patients aged ≥75 with specific tumor characteristics (e.g., 1.01-1.49 mm on head/neck/upper extremity, or 1.5-1.99 mm without high-risk features) had <5% risk of SLN positivity.

Conclusions:

• Intermediate thickness melanoma exhibits considerable heterogeneity in SLNB positivity rates.
• Identification of low-risk subgroups, particularly among older patients without high-risk features, is possible.
• These findings may aid in optimizing the use of SLNB in select melanoma patients.