Rectal screening combined with PSA is now recognized as the best primary screening method for early detection of prostate cancer. The initial suspicion of prostate cancer is usually determined by rectal examination or serum prostate-specific antigen (PSA) testing before a prostate biopsy is performed. The majority of patients with prostate cancer are diagnosed clinically by systematic puncture biopsy of the prostate to obtain a histopathologic diagnosis. In a small number of patients, prostate cancer is found incidentally in the pathology after prostate enlargement surgery. The following are the recommended methods for prostate cancer diagnosis: 1. digital rectal examination (DRE): Most prostate cancers originate in the peripheral zone of the prostate, and DRE is valuable for the early diagnosis and staging of prostate cancer. Considering that DRE may affect the PSA value, DRE should be performed after the PSA blood test. 2. prostate-specific antigen (PSA) test: PSA as a single test has a higher quality than DRE and transrectal ultrasonography (TRUS), PSA as a single test has a higher predictive rate of positive prostate cancer diagnosis compared with DRE and transrectal ultrasonography (TRUS), and can improve the diagnosis of limited prostate cancer and increase the chance of radical prostate cancer treatment. (1) Timing of PSA screening: The American Urological Association (AUA) and the American Society of Clinical Oncology (ASCO) recommend that men over the age of 50 should undergo routine DRE and PSA screening annually. For the population of men with a family history of prostate cancer, annual examinations should be performed starting at age 45. Expert consensus in Taiwan, China, pursued the US recommendations. A consensus was reached by expert discussion in China that routine PSA and DRE examinations should be performed for men over 50 years of age with lower urinary tract symptoms, and for the population of men with a family history of prostate cancer, regular examinations and follow-up should begin at age 45. PSA should be performed in men with abnormal DRE, clinical signs (such as bone pain, fractures, etc.) or imaging abnormalities, etc. There are a number of other factors that can affect serum PSA levels. Rectal finger examination can cause an elevation of PSA, but this elevation does not seem to affect the diagnosis of prostate cancer. PSA test should be performed 1 week after prostate massage, 48 hours after cystoscopy, catheterization and other operations, 24 hours after ejaculation and 1 month after prostate puncture. PSA test should be performed without acute prostatitis, urinary retention and other diseases. (2) Determination of PSA results: The current consensus at home and abroad is that a total serum PSA (tPSA) > 4.0ng/ml is abnormal. When tPSA is between 4~10ng/ml, the possibility of prostate cancer is about 25%. The serum PSA is affected by age and prostate size: 3. Transrectal ultrasonography (TRUS): The typical sign of prostate cancer on TRUS is a hypoechoic nodule in the peripheral zone, and the size of the tumor can be initially determined by ultrasound. However, TRUS is less specific for the diagnosis of prostate cancer, and the detection of a hypoechoic prostate lesion has to be differentiated from a normal prostate, BPH, PIN, acute or chronic prostatitis, and prostate infarction. Also, many prostate tumors present as isoechoic and cannot be detected on ultrasound. At present, the most important role of TRUS is to guide the systematic puncture biopsy of the prostate; 4. Prostate puncture biopsy Systematic puncture biopsy of the prostate is the most reliable test to diagnose prostate cancer; 5. Other imaging tests for prostate cancer (1) Computed tomography (CT) examination: CT is less sensitive than magnetic resonance imaging (MRI) for the diagnosis of early prostate cancer. The purpose of CT examination for prostate cancer patients is to assist clinicians in the clinical staging of the tumor. For the invasion of tumor adjacent tissues and organs and metastatic lymph node enlargement in the pelvis, the diagnostic sensitivity of CT is similar to that of MRI; (2) Magnetic Resonance Imaging (MRI/MRS) scan: MRI examination can show the integrity of the prostate envelope, whether it invades the prostate surrounding tissues and organs, and MRI can also show the invasion of pelvic lymph nodes and bone metastases. ECT can detect bone metastases 3-6 months earlier than conventional X-rays and is more sensitive but less specific. Once the diagnosis of prostate cancer is established, whole-body nuclear bone imaging is recommended (especially in cases with PSA > 20 and GS score > 7) to help determine the accurate clinical stage of prostate cancer.