We think we can establish a prognosis evaluation system for prostate cancer combined with CgA, as follows: For low-risk prostate cancer, if the patient has normal CgA level, low PSA level (such as PSA < 10 ng/mL), Gleason score ≤6, and clinical stage T1-T2a, it can be judged as low-risk prostate cancer. The gene discussed is KLK3; the disease is prostate cancer.