How Many Sentinel Lymph Nodes Should We Excise in Patients With Melanoma?

The management of many patients with early-stage melanoma includes sentinel lymph node (SLN) biopsy for prognostic and treatment planning purposes. While the minimum necessary number of SLNs to examine has been determined for patients with other malignancies, it has not been delineated in melanoma. The current study evaluates risk factors for SLN positivity and the associated number of SLNs that are necessary to examine for appropriate staging.

The National Cancer Database participant user file from 2018 to 2020 was queried for clinically node-negative patients who underwent SLN biopsy. Descriptive statistics were obtained. Analysis of variance statistical analyses were performed.

Eight thousand forty eight melanoma patients out of 48,748 were identified from 2018 to 2020 that had lymph node positivity on SLN biopsy. The median age of patients was 64. The male-to-female ratio was 1.47. Chi-squared analysis revealed that there was a statistically significant difference in positivity rate between at least two groups (P = 0.006) for primary melanoma site, male sex (P < 0.01), race, age, histologic type, Breslow thickness, and lymphovascular invasion (P < 0.001). SLN positivity rate increased with the number of SLNs examined until plateauing at 4 SLNs. There was no statistical difference between positivity for 3 SLNs and larger numbers of SLNs examined. Propensity matching revealed no statistically significant difference in positive rate when more than 2 SLNs were biopsied.

SLN positivity is proportionally related to the number of SLNs examined, suggesting that surgeons should attempt to remove a minimum of 2 SLNs for the optimal staging of patients with melanoma.