Clinical and histopathological risk factors to predict sentinel lymph node positivity, disease-free and overall survival in clinical stages I-II AJCC skin melanoma: outcome analysis from a single-institution prospectively collected database.

Background: To investigate if the tumour infiltrating lymphocytes (TILs) are able to predict the sentinel lymph node (SLN) positivity, the disease-free survival (DFS) and overall survival (OS) in clinical stages I-II AJCC primary cutaneous melanoma (PCM).

Methods: The study included consecutive patients with PCM, all diagnosed, treated and followed up prospectively. Logistic regression was used to investigate the association between DFS, OS, SLN positivity and Breslow thickness, Clark level, TIL, ulceration, lesion site, gender, regression and age.

Results: From November 1998 to October 2008, 1251 consecutive patients with PCM were evaluated. Median age was 51 (range 15-96) with 32.2% (N=393) of them older than 60; 44.8% of them were males. Of the whole series, a total of 404 patients with primary vertical growth phase (VGP) melanoma and no clinical evidence of metastatic disease underwent SLN biopsy. Of these, 74 (18.8%) had a positive SLN. In a multivariate analysis, primary melanoma on the extremities versus that on the axial locations (truncal and head/neck) (OR 0.49, 95% CI 0.25-0.98, p 0.04) and TILs (TILs versus no TILs) (OR 0.47, 95%CI 0.25-0.90, p 0.02) were predictive for lower probability of SLN involvement, while thickness (>4mm versus 0-1mm) (OR 24, 19, 95% CI 4.91-119.13, p<.001) was predictive for higher risk of SLN positivity. A multivariate stepwise analysis confirmed these results. The histological status of the SLN was the most significant predictor of DFS and OS. Patients with a negative SLN had a 5-year DFS of 75.9%, compared with 35.2% in patients with a positive SLN (p<.0001) and a 5-year OS of 88.7% versus 42.9%, respectively (p<.0001).

Conclusions: Our study demonstrates that the absence of TILs predicts SLN metastasis, in multivariate analysis the SLN positivity predicts DFS and OS.