Background. Sentinel lymph node biopsy (SLNB) is generally recommended for staging patients with melanomas ≥ 1 mm thick. However, other clinicopathologic factors in addition to thickness may also predict for nodal metastasis. We analyzed the Surveillance, Epidemiology, and End Results (SEER) database to determine the prognostic value of nodal staging and to assess which factors are correlated with SLN disease in patients with melanoma.
Materials and Methods. From 2010 to 2012, 10,013 patients with cutaneous melanoma who were treated with SLNB were identified in the SEER database. Clinicopathologic factors were compared with SLN metastasis and outcome.
Results. Overall median thickness was 1.25 mm; 3269 (32.6%), 5707 (57.0%), and 1019 (10.2%) cases were thin, intermediate thickness, and thick, respectively. Thickness was unknown in eighteen cases (0.2%). SLN metastases were found in 448/10,013 cases (4.5%); 1.5%, 4.8%, and 12.1% of thin, intermediate thickness, and thick cases had a positive SLNB, respectively. Significant predictors of SLN metastasis on multivariable analysis included thickness, mitotic rate, tumor site, race, marital status, and high school completion (P < 0.05). Overall survival was significantly worse in patients with a positive SLNB (P < 0.05). SLN status, age, presence of ulceration, mitotic rate, thickness, and poverty level were significant predictors on multivariable analysis for overall survival (P < 0.05).
Conclusions. Melanoma thickness, used in combination with unique factors such as race and marital status, may improve identification of patients at risk for SLN metastasis. Additionally, SLN status provides powerful staging information and is predictive of survival in patients with thin, intermediate thickness, and thick melanomas.