Correlation of caveolin 1 expression with disease-free survival in skin melanoma.

Abstract

e19016 Background: As clinical and histological parameters are unable to precisely predict the behavior of skin melanoma, new criteria are required to improve risk assessment. Caveolin 1 (CAV1), a scaffolding membrane protein, has been implicated in cell proliferation, death and transformation. In melanoma cell lines, CAV1 was found to have an antimetastatic role and loss of stromal CAV1 expression in lymph nodes metastases was associated with poor survival. The objectives of this analysis were to correlate CAV1 expression in primary skin melanoma cells with tumor thickness and disease free survival (DFS). Methods: CAV1 immunostaining was performed on the primary skin melanomas of 40 patients. CAV1 expression was scored semi-quantitatively using a 3-point scale: 0 (no staining), 1 (diffuse weak staining or strong staining in less then 30% of the cells) and 2 (strong staining of 30% or more of the cells). For analysis purposes, CAV1 was dichotomized as present (score 1 or 2) or absent (score 0). Primary melanoma was classified based on 2009 AJCC T-stage. DFS was measured from removal of primary skin melanoma to development of loco-regional or systemic recurrence. Pearson Chi-Square, Kaplan Meier, and Cox-Proportional Hazard Ratio were used for data analyses. Results: T-stage distribution was: Cis 12.5%, T1 32.5%, T2 22.5%, T3 17.5%, T4 15.0%. There was a clear inverse relationship between T stage and Cav 1 expression in tumor cells, with higher CAV1 expression in less invasive melanomas (P= 0.01). Fifteen patients experienced either locoregional or distant recurrence (median time to recurrence 14 months; range <1 month -105 months). Twenty-five patients remained disease free for minimum of 3 years (median 77 months; range 36 – 111 months). Presence of CAV1 in primary melanoma tumor cells was correlated with increased DFS (P = 0.05) but this association was not significant when adjusting for T stage (P=0.59). Conclusions: CAV1 expression in melanoma tumor cells correlates with clinical behavior of skin melanoma as its loss is associated with invasiveness and distant recurrence. Whether the loss of CAV1 in primary melanoma tumor cells is just an epiphenomenon or a causal event is to be decided by further work on a larger population sample.