Prostate-specific antigen (PSA) is a glycoprotein produced by prostate epithelial cells with a molecular weight of 34,000 and a normal value of <4.0 ng/ml in serum (enzyme-linked immunoassay). PSA is currently the most sensitive tumor marker for prostate cancer and is the best indicator for prostate cancer diagnosis, efficacy observation, and tracking recurrence. However, it should be noted in clinical practice that there is a partial overlap area between PSA in patients with prostate enlargement and PSA in prostate cancer. (Other causes that can cause increased PSA are still: urinary tract infection, acute prostatitis, chronic prostatitis, urinary retention/catheterization, biopsy/TURP, ejaculation/DRE, etc.) [Specimen collection] 3ml of fasting blood early in the morning was sent for testing. Normal value for all ages <4.0ng/ml (adjusted for age: 40-49 years <2.5; 50-59 years <3.5; 60-69 years <4.5; 70 years or older <6.5 ). Indications for the need for PSA testing: 1. Patient needs according to physician's recommendation. 2.With lower urinary tract symptoms. 3, Abnormal anal finger examination. 4, Progressive bone pain, especially back pain. 5.Unexplained anemia, anorexia and weight loss. 6.Unprovoked thrombosis and unilateral lower limb edema. 7.Monitoring of prostate cancer patients. The application of PSA and DRE for screening tests in elderly people aged 50 to 70 years and early diagnosis and treatment will likely significantly reduce the incidence and mortality of prostate cancer. Advocates of screening tests argue that earlier, simpler and less expensive tests are beneficial in detecting disease before the onset of obvious lesions. The estimated 6 to 12 years from screening diagnosis to clinical diagnosis is a period of time that would allow more tumors confined to the organ to be diagnosed and saved. However, opponents argue that because of the low specificity of PSA (40%) and the prevalence of latent prostate cancer, many patients suffer from unnecessary stress, biopsies, misdiagnosis, and overtreatment. According to statistics, there are fewer cases of overdiagnosis in the screening population aged 60 to 69 years than in those aged 70 to 79 years or 80 to 89 years. What's more, its treatment has the potential to increase mortality and health care costs. Theoretically, prostate cancer does not yet meet the criteria set by Wilson and Jungner et al, including a clear understanding of the natural history of the disease and adequate resources and facilities to screen susceptible populations. Prostate cancer was detected in 3% of subjects screened in the UK population, most of whom had limited lesions. A non-randomized study from Tyrol and Australia showed an 80% reduction in prostate cancer metastases and a 30% reduction in prostate cancer mortality over a six-year period. Conversely, a comparative statistic on Seattle and Connecticut showed that prostate cancer mortality was similar in both states, although diagnosis and treatment of prostate cancer was more prevalent in Seattle. Results of the European and North American randomized survey will not be available until 2008. Survival and quality of life are the ultimate issues that need to be addressed. Currently in the UK, there is little support for prostate cancer screening, although health authorities advocate counseling for asymptomatic people who request screening. PSA and prostate cancer Prior to the advent of commercial serum PSA testing in the late 1980s, acid phosphatase was the only tumor marker available for prostate cancer. This marker was highly specific for patients with bone metastases from prostate cancer, but lacked sensitivity for detecting early-stage tumors, and was even normal in more than 20% of patients with bone metastases. Before the advent of PSA, most male patients with prostate cancer were already advanced and difficult to treat once they were diagnosed. The predictive values of PSA and rectal examinations for biopsy of prostate cancer are shown in the table: PSA can be used as a serum marker to diagnose prostate cancer, but it can also help patients with staging, counseling and monitoring of prostate cancer. Here are some examples: 1. Although a small percentage of poorly differentiated prostate cancer does not express PSA, PSA values generally increase with tumor stage and tumor volume. 2, PSA together with clinical staging and Gleason score can predict the tumor stage and evaluate the outcome after radical treatment of prostate cancer. 3.If PSA>10ng/ml, then more than 50% of patients have lesions outside the prostate. 4.If PSA>20ng/ml, then less than 5% of patients have lymph node metastasis and only 1% of patients have bone metastasis. 5.If PSA>50ng/ml, then 66% of patients may involve lymph nodes (ducts) and 90% of patients involve seminal vesicles. 6, In fact PSA should not be detected after radical resection of limited prostate cancer. 7. After radical prostatectomy, PSA elevation appears greater than 8 years earlier than prostate cancer metastasis. 8. In 80% of patients with metastatic prostate cancer, PSA decreases to within the normal range within 4 months after hormone therapy; an elevated PSA within 18 months after starting hormone therapy is indicative of worsening prostate cancer. PSA is specific for the prostate, but not for prostate cancer. This is because there are other prostate pathologies that can cause PSA to rise.