The sentinel node invasion level (SNIL) as a prognostic parameter in melanoma

Area of Science:

• Oncology
• Pathology
• Surgical Oncology

Background:

• Sentinel lymph node (SN) tumor burden is increasingly vital for melanoma staging and may be incorporated into future N classifications.
• Accurate assessment of SN metastasis is critical for determining prognosis and guiding treatment decisions in melanoma patients.

Purpose of the Study:

• To investigate the prognostic significance of melanoma infiltration patterns within anatomically defined lymph node substructures.
• To develop and validate a Sentinel Lymph Node Invasion Level (SNIL) system for stratifying melanoma patient outcomes.

Main Methods:

• Retrospective cohort study of 1250 patients with SN biopsy for melanoma.
• Detailed pathological analysis of SN substructure infiltration (lymph vessels, sinuses, cortex, paracortex, medulla, capsule).
• Classification of 338 SN-positive patients into three SNIL groups based on invasion patterns; survival analysis using Kaplan-Meier and Cox models.

Main Results:

• The SNIL system significantly stratified SN-positive patients into distinct groups based on recurrence-free survival (RFS), melanoma-specific survival (MSS), and nodal basin recurrence.
• Patients with SNIL 1 (minimal invasion) had MSS similar to SN-negative patients.
• Advanced invasion into the medulla or capsule (SNIL 3) indicated a poor prognosis, with significantly higher recurrence rates and lower MSS.

Conclusions:

• The SNIL system provides valuable prognostic information beyond simple SN metastasis detection.
• SNIL effectively stratifies melanoma patients based on the extent of lymph node involvement, aiding in risk assessment.
• This classification may optimize the selection of adjuvant therapies by better defining the benefit-risk ratio for individual patients.