Use and Costs of Sentinel Lymph Node Biopsy in Non-Ulcerated T1b Melanoma: Analysis of a Population-Based Registry

Background The utility of sentinel lymph node biopsy (SLNB) for non-ulcerated T1b melanoma is debated and associated costs are poorly characterized. Prior work using institutional registries may overestimate the incidence of nodal positivity in this population. Objective The aim of this study was to estimate the use of SLNB, positivity prevalence, and procedural costs in patients with non-ulcerated T1b melanoma using a population-based registry. Methods We identified patients with clinically node-negative, non-ulcerated melanoma 0.8-1.0 mm thick (T1b according to the 8th edition standard of the American Joint Committee on Cancer) in the Surveillance, Epidemiology, and End Results database from 2010 to 2016. The prevalence of SLNB procedures and positive sentinel nodes were calculated. Factors associated with SLNB and sentinel node positivity were assessed using logistic regression. Medicare reimbursement costs and patient out-of-pocket expenses for SLNB and wide local excision (WLE) versus WLE alone were estimated. Results Among 7245 included patients, 3835(53%) underwent SLNB, 156 (4.1%, 95% confidence interval 3.5-4.7) of whom had a positive SLNB. Younger age, >1 mitosis per mm(2), female sex, and truncal tumor location were associated with higher odds of positivity. The estimated SLNB cost to identify one patient with stage III disease was $71,700 (range $54,648-$83,172). Out-of-pocket expenses for a Medicare patient were estimated to be $652 for a WLE and SLNB and $79 for a WLE alone. Conclusions In this population-based study, only 4% of selected non-ulcerated T1b patients had a positive SLNB, which is lower than prior reports. At the population level, SLNB is associated with high costs per prognostic information gained.

Automated summary

The study estimated the use of SLNB, positivity prevalence, and procedural costs in patients with non-ulcerated T1b melanoma using a population-based registry. Results showed that only 4% of patients had a positive SLNB, lower than previous reports, and factors such as age, mitosis rate, sex, and tumor location were associated with positivity. The study highlighted the high costs per prognostic information gained with SLNB at the population level.