This observational study is being done to identify possible biomarkers that can be used for prognostic, prediction, or monitoring considerations in patients with melanoma or non-melanoma skin cancer undergoing treatment. Investigators plan to investigate blood factors which include circulating tumor cells (CTCs - i.e., cancer cells that can be detected in the blood) and their associated protein and mRNA expression; circulating tumor DNA (ctDNA - i.e., pieces of DNA from cancer cells that can be found in the blood); and tumor-derived exosomes (i.e., extracellular vesicles generated by cancer cells that carry nucleic acids, proteins, and metabolites).
