Gender, age, and Breslow thickness are significant predictors for sentinel lymph node biopsy (SLNB) positivity in thin melanoma, according to a study published in the Journal of the American Academy of Dermatology.

The investigators sought to assess predictors of SLNB positivity in patients with thin melanomas. A total of 9186 patients with cutaneous melanoma with Breslow thickness ≤1.00 mm who received an SLNB between 2004 and 2014 were identified from the National Cancer Database and included in multivariate analysis. Logistic regression was used to analyze predictors of SLNB positivity.

Patients who were <60 years of age and had a Breslow thickness of >0.8 mm were at a significantly increased risk for a positive SLNB (P <.001 and P =.03, respectively). Additionally, males were at an increased risk (odds ratio [OR] 1.32; 95% CI, 1.07-1.63; P <.001). 

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The presence of dermal mitoses increased the likelihood of SLNB positivity by 95% (OR 1.95; 95% CI, 1.53-2.50; P <.001), ulceration increased the likelihood of SLNB positivity by 63% (OR 1.63; 95% CI, 1.21-2.18; P <.001), and Clark level IV to V increased the likelihood of SLNB positivity by 48% (OR 1.47; 95% CI, 1.19-1.85; P <.001). The number of comorbidities, location of tumor, histologic type, and laterality did not affect SLNB positivity, however.

The investigators concluded that because the National Cancer Database began releasing SLNB data in 2012, only approximately 3 years of follow-up data are available, rendering it difficult to demonstrate definitely the effects of mitoses and Clark level on survival data when adjusting for SLNB positivity in this cohort. They recommend that dermatopathologists continue to assess and report dermal mitotic rates and Clark levels, as they might be key to establishing clear precise guidelines regarding SLNB in patients with thin melanomas.

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Conic RZ, Ko J, Damiani G, et al. Predictors of sentinel lymph node positivity in thin melanoma using the National Cancer Database [published online September 18, 2018]. J Am Acad Dermatol. doi: 10.1016/j.jaad.2018.08.051