To evaluate the potential of AQP5 as a novel prognostic marker of prostate cancer, we employed immunohistochemical, immunofluorescence, and FISH methods to detect the expression and amplification of AQP5 gene in clinical samples and prostate cancer cells, and immunofluorescence in situ hybridization (imFISH) staining to detect CTCs. This evidence concerns the gene AQP5 and Familial prostate cancer.