Relationship between age and likelihood of lymph node metastases in patients with intermediate thickness melanoma (1.01-4.00 mm): A National Cancer Database study

Background: There is large variability in the risk of sentinel lymph node (SLN) positivity among patients with intermediate thickness melanoma (ITM), with a subgroup of patients exhibiting a low risk of nodal disease. Objective: To identify a group of patients with ITM for whom the risk of nodal disease is low. Methods: A retrospective cohort of patients with ITM who underwent wide excision and nodal evaluation from 2010 to 2013 was identified by using the National Cancer Database and analyzed for the presence of nodal disease. Classification and regression tree analysis identified the most important factors used in a model to identify groups at low risk of SLN positivity. Results: Of 23,440 patients, 14.7% were found to have nodal metastasis. On classification and regression tree analysis, patients older than 55 years without lymphovascular invasion and with a lesion thickness less than 1.7 mm had an SLN positivity rate of 4.9%. A model using age and thickness in nonulcerated patients identified a low-risk subgroup with a corresponding SLN positivity rate of 4.7%. Limitations: This was a retrospective study, and the model developed requires prospective validation. Conclusions: Patient age is an important factor in estimating risk of SLN in patients with ITM and may help identify patients without ulceration who may be safely spared an SLN biopsy.