50: Sentinel Lymph Node Biopsy in Patients with t1a Cutaneous Malignant Melanoma

Friday, March 11, 2022

1:31 PM – 1:39 PM CST

Location: Chantilly East

Abstract Presenter(s)

Adrienne B. Shannon, MD

Surgical Resident, Postdoctoral Researcher
Hospital of the University of Pennsylvania
Philadelphia, Pennsylvania, United States

Disclosure: I do not have any relevant financial / non-financial relationships with any proprietary interests.

Participants should be aware of the following financial/non-financial relationships:

Adrienne B. Shannon, MD: I do not have any relevant financial / non-financial relationships with any proprietary interests.

Introduction:

Sentinel lymph node (SLN) biopsy is not routinely recommended for T1a cutaneous melanoma. Prognostic factors associated with SLN positivity (SLN+) in this population are poorly characterized.

Methods: Patients with pathologic T1a (< 0.80 mm, non-ulcerated) cutaneous melanoma from five centers from 2001-2020 who underwent wide local excision with SLN biopsy were included in the study. Patient and tumor characteristics associated with SLN+ were analyzed by univariate and multivariable logistic regression analyses. Age was dichotomized into the < 42 (25% quartile cutoff) and ≥42 years.

Results: Among 965 patients with T1a melanoma, the SLN positivity rate was 4.4% (N=43). Overall median age and tumor thickness were 53 (interquartile range [IQR] 42-63) years and 0.60 (IQR 0.50-0.70) mm, respectively. Following multivariable analysis, factors associated with SLN+ were age < 42 years (SLN+ rate 7.5% vs 3.7%, odds ratio [OR] 2.20, p 0.02), head/neck primary tumor location (9.2% vs 4%, OR 2.79, p 0.04), lymphovascular invasion (LVI) (21.4% vs 4.2%, OR 6.22, p 0.01), and >2 mitoses/mm² ( 8.2% vs 3.4%, OR 2.32, p 0.02). Patients < 42 years with >2 mitoses/mm² (N=40) had a SLN+ rate of 17.5%. With a median follow-up time of 73 (IQR 31-138) months, five-year disease-specific survival (DSS) in SLN+ versus SLN- patients was 90.7% versus 99.5% (p< 0.0001), and five-year recurrence-free survival (RFS) in SLN+ versus SLN- patients was 81.4% versus 95.6% (p< 0.0001), respectively.

Conclusions: SLN+ is low overall in patients with T1a melanomas, but younger age, head/neck primary site, LVI, and mitogenicity may confer a higher risk of SLN+. SLNB may be selectively considered in the setting of these high-risk factors.

Learning Objectives:

Upon completion, the participant will be able to understand the incidence of positive sentinel lymph node metastases in T1a cutaneous melanoma.
Upon completion, the participant will be able to understand the predictors of positive sentinel lymph nodes in patients with T1a cutaneous melanoma.
Upon completion, the participant will be able to risk-stratify T1a melanoma patients for sentinel lymph node positivity and can provide an informed discussion on the role of sentinel node biopsy.