The PSA test is a blood test used primarily to screen for prostate cancer.

The test measures the amount of prostate-specific antigen (PSA) in your blood. PSA is a protein produced by both cancerous and noncancerous tissue in the prostate, a small gland that sits below the bladder in males.

PSA is mostly found in semen, which also is produced in the prostate. Small amounts of PSA ordinarily circulate in the blood.

The PSA test can detect high levels of PSA that may indicate the presence of prostate cancer. However, many other conditions, such as an enlarged or inflamed prostate, also can increase PSA levels. 

Prostate cancer is common, and it is a frequent cause of cancer ath. Early detection may be an important tool in getting appropriate and timely treatment.

Prostate cancer can cause elevated levels of PSA. However, many noncancerous conditions also can increase the PSA level. The PSA test can detect high levels of PSA in the blood but doesn't provide precise diagnostic information about the condition of the prostate.

The PSA test is only one tool used to screen for early signs of prostate cancer. Another common screening test, usually done in addition to a PSA test, is a digital rectal exam.

 Abnormal results in these tests may lead your doctor to recommend a prostate biopsy.

During a prostate biopsy, samples of prostate tissue are removed for laboratory examination. A diagnosis of cancer is based on the biopsy results.