Nodal surveillance and adjuvant therapy in sentinel lymph node-positive melanoma patients.

e21586 Background: Since the publication of the Multicenter Selective Lymphadenectomy Trial-II (MSLT-II) in 2017, completion lymph node dissection (CLND) for sentinel lymph node (SLN)-positive patients has mainly been deferred for ultrasound surveillance of the nodal basin. Additionally, there is now widespread use of adjuvant therapy in these patients. However, CLND was required for the major adjuvant therapy trials, therefore information on recurrence patterns in SLN-positive patients receiving adjuvant therapy without CLND is limited. Methods: In this retrospective cohort study of patients with SLN-positive melanoma identified from 2017 to 2021 at a single institution, the primary aim was to evaluate the incidence of local, nodal, in-transit, and distant recurrence in patients receiving adjuvant therapy with nodal surveillance compared to nodal surveillance alone. Method of detection of recurrence, compliance with ultrasound surveillance, and clinicopathologic risk factors were also assessed. Chi-square tests were used to evaluate for any associations between clinicopathologic characteristics, initial location of recurrence, and receipt of adjuvant therapy. Results: Of 157 SLN-positive melanoma patients identified, 21 (13%) received CLND and 13 (8%) had insufficient follow-up information for inclusion. Among 123 eligible patients (mean 55 years, 54% male), the median follow-up time was 24.5 months during which 33 (27%) patients recurred. Of 13 patients with isolated nodal recurrence, three were detected by ultrasound alone, five were detect by CT alone, and five were detected by both CT and ultrasound (Table). 90 (73%) patients in the cohort received adjuvant therapy (92% anti-PD1, 6% BRAF/MEK, 2% anti-CTLA4). The main reasons for exclusion of adjuvant systemic therapy were minimal nodal disease or patient refusal. The average time to recurrence was 13.4 months. There were no significant differences in recurrence rates (p = 0.49) or location of initial recurrence (p = 0.64) by receipt of adjuvant therapy. 29 (24%) patients missed more than one ultrasound. Ultrasound surveillance was most frequently missed due to clinician omittance or patient distance to clinic. Conclusions: In our cohort of SLN-positive melanoma patients, the majority received adjuvant anti-PD1 immunotherapy and were followed in surveillance without CLND. There was no significant difference in recurrence patterns based on receipt of adjuvant therapy and a quarter of nodal recurrences were detected by ultrasound alone. Our results support the use of ultrasound surveillance in addition to cross-sectional imaging to monitor for recurrence in these high-risk patients.[Table: see text]