Acid ceramidase (ASAH1) expression was significantly increased in PIN when compared to non-malignant and primary prostate cancer tissue (P ≤ 0.05), and was significantly reduced in metastatic tissue when compared to primary prostate cancer (P ≤ 0.01), PIN (P ≤ 0.0001), and non-malignant tissue (P ≤ 0.01). This evidence concerns the gene ASAH1 and prostate intraepithelial neoplasia.