KLK3 and metastatic malignant neoplasm in the lymph nodes: First, the 24,054 PCa patients with a PSA level < 4 ng/ml had more favorable clinical characteristics than those with other PSA level(4–10 ng/ml, 10–20 ng/ml and > 20 ng/ml): the patients with a PSA level < 4 ng/ml were younger and diagnosed with lower T stages (T1–2), lower Gleason grades and lower lymph node metastasis rates.