Malignant melanoma, one of the three major skin cancers, is associated with the worst outcome due to its propensity to metastasize and its resistance to therapy. It afflicts mainly Caucasian populations and due to its increasing prevalence, approximately, one in 60 persons will be diagnosed with melanoma during their lifetime. Within Europe, melanoma has become the most common cancer in young adults. About 20 percent of melanomas progress to regional and distant metastases. Additionally, development of secondary primary cancers in melanoma patients contributes to enhanced personal and financial burden. The involvement of genetic factors in combination with environmental factors and individual phenotypes are known to increase the risk of primary melanoma. However, the genetic factors that pre-dispose to development of metastases or second primary cancers in melanoma patients remain mostly unknown. Taking advantage of advanced techniques, we propose to identify genetic alterations having a prognostic value in development of metastases and second melanomas in asymptomatic patients that have undergone surgical treatment for primary cutaneous melanoma. We will use a unique collective collection of samples from over 2200 melanoma patients (including young adults and elderly patients) of whom more than 450 developed metastases or second melanomas, recruited at the partner centers. We propose to use a two-stage strategy to discover genetic markers prognostic of metastases and second melanomas. In the discovery phase we will use exome-sequencing and genome wide analysis of retroelements to screen tumor and normal DNA from a subgroup of melanoma patients with and without metastases and second melanomas. We will then validate identified markers in the entire pooled collection of tumors tissue samples with clinical data available within the resources of the consortium. This study will reveal genetic markers that can be useful in identifying patients who run a substantial risk of developing metastases or second melanomas. Early identification of such patients remains a valid medical issue. The development of a prognostic test based on genetic markers for clinical use is the ultimate goal of the proposal.