I. Total prostate-specific antigen (TPSA) Mainly related tumors: prostate cancer. Other related tumors: certain gynecological tumors, polycystic ovary syndrome, breast cancer. Other influencing factors: Prostatitis and prostate enlargement can cause elevation. PSA is a specific marker for prostate cancer and is currently recognized as the only organ-specific tumor marker. Elevated serum TPSA generally indicates the presence of a lesion in the prostate (prostatitis, benign hyperplasia or cancer). TPSA is one of the most important indicators for the detection and early detection of prostate cancer, with a positive threshold of greater than 10 μg/L and a diagnostic specificity of 90-97% for prostate cancer. TPSA can also be used for screening and early diagnosis of prostate cancer in high-risk groups and is the first tumor marker recommended by the American Cancer Society for screening men over 50 years of age for prostate cancer. The TPSA assay can also be used to monitor the condition and outcome of patients with prostate cancer or those receiving hormone therapy. 90% of patients with postoperative prostate cancer have serum TPSA values that can be reduced to undetectable trace levels, and if the serum TPSA value increases after surgery, it indicates the presence of residual tumor. For those with significant efficacy after radiotherapy, more than 50% of patients had their serum TPSA reduced to normal within 2 months. Free prostate-specific antigen (FPSA) Main relevant tumors: prostate cancer. Other related tumors: certain gynecological tumors and breast cancer. Other influencing factors: Prostate enlargement can cause elevation. A single total serum PSA (TPSA) assay does not clearly identify prostate cancer from benign prostatic hyperplasia, mainly because there is crossover between the two groups of patients in the concentration range of 2-20 ng/ml. In contrast, FPSA/TPSA is not affected by this factor and age, and the FPSA/TPSA ratio is used to identify prostate cancer or benign prostatic hyperplasia. The FPSA/TPSA ratio is significantly lower in patients with prostate cancer and higher in patients with benign prostatic hyperplasia. The FPSA test is mainly indicated for untreated patients with TPSA values of 2-20 ng/ml. When TPSA values are below 2 ng/ml or above 20 ng/ml, the FPSA/TPSA ratio is not used to differentiate prostate cancer from benign prostatic hyperplasia.