DKK1 and Familial prostate cancer: Interestingly, when assessing DKK-1 serum levels in patients with prostate cancer (n = 80) compared to benign prostate hyperplasia (n = 23), we did not see a significant increase (25.3 ± 6.0 vs. 27.9 ± 12.9) in DKK-1 values.