Influence of regression, its extent and tumor-infiltrating lymphocytes on sentinel node status, relapse, and survival in a 10-year retrospective study of melanoma patients.

This case-control study seeks to investigate the influence of histological findings, specifically regression, its extent and tumor-infiltrating lymphocyte (TILs), on result of sentinel lymph node (SLN) biopsy, 5-year melanoma-specific survival (MSS), and relapse-free survival (RFS). We included all patients with cutaneous melanoma who underwent SLN biopsy at the Melanoma Center of the University of Brescia, following the Italian Association of Medical Oncology National guidelines from January 2008 to August 2018. Regression and its extent (<75 or ≥75%) and the presence of TILs were reevaluated by a trained dermatopathologist, adhering to the 2017 College of American Pathologists Cancer Protocol for Skin Melanoma. These patients were followed up for 5 years. Our study uncovered significant associations between regression and male sex ( P  < 0.05), melanoma location on the trunk, upper limbs, and back ( P  = 0.001), ulceration ( P  < 0.05), lower Breslow thickness ( P  = 0.001), and the presence of lymphocytic infiltration (both brisk and nonbrisk) ( P  < 0.001). Regression and its extent, however, did not appear to affect SLN positivity ( P  = 0.315). Similarly, our data did not reveal a correlation between TILs and result of SLN biopsy ( P  = 0.256). When analyzing MSS and RFS in relation to the presence or absence of regression and TILs, no statistically significant differences were observed, thus precluding the need for logistic regression and Kaplan-Meier curve analysis. This study's findings underscore that regression and TILs do not appear to exert an influence on sentinel lymph node status, MSS, or RFS in our cohort of patients.