Diagnosis - PSA Blood Test



PSA refers to Prostate-Specific-Antigen, a type of protein produced by the cells of the prostate gland. PSA test serve as a tumor marker to detect presence of prostate cancer.

The PSA test measures the level of PSA in the blood. The higher the PSA level, the higher possibility of cancer. However, there are other possible reasons for high PSA level. Common benign prostate condition in older men such as inflammation of the prostate (prostatitis) and benign prostatic hyperplasia (BPH) and enlargement of the prostate can also raise PSA level.

The U.S Food and Drug Administration (FDA) has cleared the use of PSA test together with a digital rectal exam (DRE) to detect prostate cancer in men above the age of 50.

General guideline for PSA reading :

• 0 to 2.5 ng/mL is low.
• 2.6 to 10 ng/mL is slightly to moderately elevated.
• 10 to 19.9 ng/mL is moderately elevated.
• 20 ng/mL or more is significantly elevated.

PSA test have some limitations and is regarded to be controversial. Limitations in PSA test may include false positive test where PSA level increase have nothing to do with cancer. Only 25 to 30% of positive PSA test is confirmed to be cancerous.

On the other hand, a false negative test can also happen. Most tumor is slow growing and may take decades before they become large enough to produce symptoms. In other word, PSA test may not be able to detect early development of prostate cancer.

The reason some doctors refer PSA tests as controversial is because it can detect the presence of cancer that may or may not be dangerous in nature. A patient may undergo a biopsy to determine if the cancer is malignant. Biopsies can be an invasive procedure that can result in bleeding or infection. Moreover, doctors can sometimes 'miss' the targeted spot and took sample of tissue from other part of nearby organ instead of the prostate, resulting in a wasted effort. Treatments for prostate cancer can cause complications such as incontinence or erectile dysfunction.

Doctors generally advise men above the age of 50 to perform an annual PSA screening, which is covered by Medicare. However, if you belong to higher risk group, routine screening can be done starting at age 40 or 45.

Studies are underway to finetune PSA test to be customizable to a patient's age, change of reading in PSA level (velocity), ethnic group, prostate size, type of protein detected and other factors to produce a more accurate picture.

One of the successful development on PSA test is comparing 'free' PSA and 'bound' PSA in free PSA test. This test can pin point the possiblity of prostate cancer more accurately.