Survival outcomes of stage IIB/IIC cutaneous melanoma treated with wide local excision and adjuvant immunotherapy without sentinel lymph node biopsy

Mahaasrei Ghosh; Brandon Toliver; Hisakazu Hoshi

doi:10.1200/JCO.2026.44.16_suppl.9563

9563Background: The Multicenter Selective Lymphadenectomy Trial-1 (MSLT-1) reported no significant difference in 10-year overall survival (OS) in patients with thick melanomas who had only wide local excision (WLE) versus WLE and sentinel lymph node biopsy (SLNB). With expanded immunotherapy eligibility for stage IIB/C melanoma per KEYNOTE-716, does omission of sentinel node negatively impact nodal basin disease control? Thus, we studied patients with stage IIB/C cutaneous melanoma treated with WLE and adjuvant pembrolizumab. Methods: We performed a single-institution retrospective review and included patients with stage IIB/C cutaneous melanoma treated with only WLE and adjuvant pembrolizumab with at least 6 months of follow-up. The primary endpoints were OS and cumulative incidence of nodal metastasis (CINM). Secondary endpoints were recurrence-free survival (RFS) and nodal metastasis-free survival (NMFS). Survival was estimated via Kaplan-Meier survival analysis and compared to the thick melanoma observation arm of MSLT-1. Results: Thirty-three patients met inclusion criteria between 2021-2025. Our sample was 58% male, 100% White, non-Hispanic, and median age at surgery was 59 ± 13 years. Twenty-sex (79%) patients were clinical group stage IIB. Tumor subtypes included acral lentiginous (3%), desmoplastic (3%), nodular (45%), spindle cell (3%), and superficial spreading (24%). Median follow-up was 24.3 ± 12.3 months. Four deaths occurred at 11, 17, 32, and 42 months, and OS probability was 96.2% at 12 months and 84.0% at 36 months. We observed 11 recurrences (33.3%). Six occurred in regional lymph nodes at 3, 3, 7, 7, 20, and 34 months, and 5 were distant metastases at 6, 11, 19, 20, and 25 months. At 12 months, RFS probability was 80.4%, 65.9% at 24 months, and 47.9% at 36 months. The probability of NMFS was 87.5% at 12 months, 82.8% at 24 months, and 69.0% at 36 months. Our CINM, over a median follow-up duration of 24.3 ± 12.3 months, was 18.2%, of which 3 began nivolumab/relatlimab and had complete radiological response and no subsequent recurrence. Of the 5 distant metastases, 3 underwent radiation or surgery for brain lesions and 1 began nivolumab/relatlimab for a chest wall nodule, both groups had complete radiologic response with no recurrence. Per MSLT-1, melanoma-specific survival of thick melanomas was between 76.1 ± 5.2% and 53.8 ± 7.6% at 60 months, and CINM was 33.2 ± 4.5% at 36 months. Conclusions: In our cohort, OS and CINM were comparable or better to the thick melanoma observation arm of MSLT-1. Our data suggests that omission of SLNB is highly likely to not negatively impact outcomes and may be offered to patients with significant operative risk. A larger sample with longer follow-up is needed to substantiate this conclusion.

Survival outcomes of stage IIB/IIC cutaneous melanoma treated with wide local excision and adjuvant immunotherapy without sentinel lymph node biopsy

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