Outcomes in clinical stage IB cutaneous melanoma managed with only wide local excision.

INTRODUCTION: Standard treatment of IB cutaneous melanoma is wide local excision with sentinel lymph node biopsy. Due to the low positivity rate, cost, complications, and limited management changes associated with positive sentinel lymph node biopsy for clinical stage IB melanoma, we sought to determine if omission of sentinel lymph node biopsy impacted outcomes. METHODS: We performed a single-institution retrospective study including patients with clinical stage IB (pT1b/2a, cN0, and cM0) cutaneous melanoma who underwent wide local excision with at least 6 months of follow-up. Primary end points were melanoma-specific survival and recurrence-free survival, and secondary end points were patterns of recurrence. Survival was estimated with Kaplan-Meier analysis. RESULTS: We identified 125 patients from 2015 to 2025. The sample was 49.6% male, with a median age of 59 years. By the National Cancer Comprehensive Network risk thresholds, 34 (27.2%) and 43 (34.4%) exceeded 10% predicted sentinel lymph node + risk per Memorial Sloan Kettering and Melanoma Institute of Australia, respectively. Primary lesion sites were 62.4% extremity, 36% trunk, and 1.6% head and neck. The predominant histologic subtype was superficial spreading (75.2%). Median follow-up was 43.2 months. Melanoma-specific survival probability was 99.1% at 13 months and 90.8% at 62 months. Eleven recurrences (8.8%) were observed: 2 (1.6%) regional lymph node, 4 (3.2%) distant, and 5 (4.0%) in-transit or local. Recurrence-free survival probability was 96.6% at 20 months and 82.7% at 60 months. CONCLUSIONS: Our data suggest that sentinel lymph node biopsy does not confer regional nodal basin control in clinical stage IB cutaneous melanoma, and its omission does not appear to negatively impact melanoma-specific survival or recurrence-free survival.