A. J. Sinnamon1, M. G. Neuwirth1, R. L. Hoffman1, D. E. Elder2, X. Xu2, R. R. Kelz1, R. E. Roses1, D. L. Fraker1, G. C. Karakousis1 2Hospital Of The University Of Pennsylvania,Department Of Pathology,Philadelphia, PA, USA 1Hospital Of The Univerity Of Pennsylvania,Endocrine And Oncologic Surgery,Philadelphia, PA, USA
Introduction:
While the association of age with nodal metastases and outcomes in patients with melanoma has been recognized and variably reported upon, the influence of age on nodal positivity in patients with thin melanoma has been less well studied, limited by few events in institutional experiences. Using a large national dataset we study the association of age and nodal positivity in thin melanoma and its implications on current recommendations for sentinel lymph node biopsy in this patient population.
Methods:
Patients with clinical stage I 0.50-1.0mm thin melanoma diagnosed from 2010-2013 who underwent wide excision and had any LNs pathologically evaluated were identified using the National Cancer Data Base (NCDB). Nodes were defined as either positive or negative based on presence of any metastatic disease. Age was categorized as <40 years, 40-64 years, and ≥65 years. Clinicopathologic factors associated with LN positivity were identified using chi-square or Fisher exact method as indicated. Multivariable logistic regression was performed to identify predictors of LN positivity.
Results:
From 2010-2013, 8772 patients underwent wide excision and had evaluation of regional LNs. Of these, 333 were found to have nodal spread, for an overall positivity rate of 3.8%. Median age was 56y (IQR 46-67y) in those with negative LNs and 52y (IQR 41-61y) with LN disease (p<0.001). By multivariable analysis, age≥65 years, thickness≥0.76mm, increasing Clark level, mitoses, ulceration, and acral lentiginous or epithelioid histology were independently associated with LN positivity. Age was found to reliably stratify patients for LN positivity among other high risk features, namely tumor depth, mitogenicity, and ulceration status (figure). Patients <40yo with T1a tumors<0.76mm (who would not generally be recommended SLN biopsy) had LN positivity rate of 5.56% (18/324 patients); conversely, patients ≥65yo with T1b tumors ≥0.76mm (who would generally be recommended for SLN biopsy) demonstrated LN positivity rate of 3.87% (37/956). This pattern remained unchanged if including Clark level IV/V as a worrisome feature in addition to mitogenicity and ulceration.
Conclusion:
Current guidelines for SLN biopsy in patients with thin melanoma focused on tumor variables may be too restrictive in young patients and overly permissive among patients ≥65 years using a 5 percent threshold for LN positivity; patient’s age should be an important factor when counseling these patients for lymph node evaluation.
