Long-term follow-up of patients with minimal sentinel node tumor burden (< 0.1mm) according to Rotterdam criteria: A study of the EORTC Melanoma Group

Abstract

9005 Background: Many studies have identified Sentinel Node (SN) tumor burden as a prognostic factor for additional non- SN (NSN) positivity and / or disease-free (DFS) and melanoma specific survival (MSS). It remains unclear if pts with minimal SN tumor burden can safely be managed without Completion Lymph Node Dissection (CLND). Pts with minimal SN tumor burden might be at risk for late recurrences (> 5 years). Methods: Slides of 595 SN positive patients were reviewed for this pan-European study collaboration in 5 major centers. Slides were reviewed for the microanatomic location and SN tumor burden according to the Rotterdam Criteria (< 0.1mm, 0.1 - 1.0mm and > 1.0 mm) for the maximum diameter of the largest metastasis. MSS, DFS and distant metastasis-free survival (DMFS) rates were calculated, as was NSN positivity. Results: In 595 SN positive pts, the mean and median Breslow thickness was 4.73 and 3.5 mm. Ulceration was present in 51% of melanomas. 67 pts had metastases < 0.1 mm (11%), 226 pts (38%) had 0.1 - 1.0 mm metastases and 302 pts had metastases > 1.0 mm (51%). Mean and median follow-up was 48 and 40 months for all patients (range 1 - 172). Patients with metastases < 0.1 mm had mean and median follow-up of 61 and 57 months, 46% (31pts) had follow up > 5 years and 25% (17 pts) had follow-up longer than 80 months (range 3 - 132). 5-year MSS rates were 94% for metastases < 0.1 mm, 70% for 0.1 - 1.0 mm and 57% for > 1.0 mm (p<0.001). 5-year DMFS rate was 91% for metastases < 0.1 mm. NSN positivity occurred in 5% of < 0.1mm, 17% of 0.1 - 1.0 and 29% of metastases > 1.0 mm (p<0.001). Conclusions: This large multicenter experience (n=595) has demonstrated that long-term follow-up of melanoma patients with minimal SN tumor burden (< 0.1 mm) indicates very low relapse rates and excellent MSS, seemingly identical to SN negative patients. With prolonged follow-up, an increase in the occurrence of relapses of any kind between 5 and 10 years follow up has not been identified, and excellent 10-year survival rates are expected. No significant financial relationships to disclose.