Prostate-specific antigen (PSA) is a protein produced by both cancerous (malignant) and noncancerous (benign) prostate tissue. PSA helps liquefy the semen. A small amount enters the bloodstream. Cancer cells usually make more PSA than do benign cells, causing PSA levels in your blood to rise. However, determining what a high PSA score means can be complicated. Besides the PSA number itself, your doctor will consider a number of other factors to evaluate your PSA scores:
* Your age
* The size of your prostate gland
* How quickly your PSA levels are changing
* Whether you're taking medications that affect PSA measurements, such as finasteride (Propecia, Proscar), dutasteride (Avodart) and even some herbal supplements
When elevated PSA isn't cancer
While high PSA levels can be a sign of prostate cancer, a number of conditions other than prostate cancer also can cause PSA levels to rise. These other conditions could cause what's known as a "false-positive" — meaning a result that falsely indicates you might have prostate cancer when you don't. Conditions that could lead to an elevated PSA level in men who don't have prostate cancer include:
* Benign prostate enlargement (benign prostatic hyperplasia)
* A prostate infection (prostatitis)
* Other less common conditions
False-positives are common. Only about one in four men who have a positive PSA test turns out to have prostate cancer.
