MMP9 and cutaneous melanoma: Overall, the results of the present study confirm that the occurrence of circulating-free DNA BRAFV600E mutation is a negative prognostic factor of cutaneous melanoma; furthermore, MMP-9 may be considered a prognostic indicator of response to BRAF inhibitors only in the subset of patients harboring the circulating-free DNA BRAFV600E mutation supporting the notion that MMP-9 is associated with the MAPK pathway.