About Cesium-131

Diagnosing Prostate Cancer

Prostate-specific antigen (PSA)

PSA is a protein produced by the cells of the prostate gland.  It is found in the blood and can be measured with a simple blood test.  Because PSA can be used to detect disease, it is sometimes called a biological marker or tumor marker.  Normally, men have low levels of PSA in their blood.  An elevated PSA level may be indicative of underlying prostate disease. Prostate cancer may cause a rise in PSA but this finding alone is not proof of prostate cancer. Other common reasons for an elevated PSA are prostatitis (inflammation of the prostate) and benign prostatic hyperplasia (BPH) (enlargement of the prostate). There is no evidence that prostatitis or BPH causes cancer, but it is possible for a man to have one or both of these conditions and develop prostate cancer as well. In some cases the prostate naturally produces more PSA than others. 

Elevated PSA levels alone do not give doctors enough information to distinguish between benign prostate conditions and cancer. However, the doctor will take the result of the PSA test into account when deciding whether to check further for signs of prostate cancer.

Prostate-Specific Antigen (PSA) Test & Digital Rectal Exam (DRE)

As men age, both benign prostate conditions and prostate cancer become more frequent. 

The U.S. Food and Drug Administration (FDA) has approved the use of the PSA test in combination with a digital rectal exam to 1) help detect prostate cancer in men and 2) to monitor patients with a history of prostate cancer to see if the cancer has recurred.

The PSA test is a measurement of the level of PSA in the blood. The test consists of a single blood draw that is then sent to a laboratory where the amount of PSA in the blood is measured.  The amount of PSA is usually reported as nanograms of PSA per milliliter (ng/mL) of blood. In the past, most doctors considered PSA values below 4.0 ng/mL as normal. However, recent research shows men with PSA levels below 4.0 ng/mL can have prostate cancer ¹.

There is no specific normal or abnormal PSA level. The higher a man’s PSA level, the more likely it is that cancer is present. But because various factors (such as age) can cause PSA levels to fluctuate, one abnormal PSA test does not prove cancer is present or necessarily indicate a need for other diagnostic tests. When PSA levels continue to rise over time, other tests may be needed.

DRE is a standard way to check the prostate. During a DRE, a physician inserts a lubricated, gloved finger into the rectum and feels the prostate gland through the rectal wall to check for bumps or lumpy areas. The exam takes roughly 15 seconds.

The Prostate Biopsy

If symptoms or test results suggest a risk of cancer, a biopsy will be necessary to determine a definitive diagnosis.  A prostate biopsy is usually performed in the Urologist’s office.  During a biopsy, several samples of prostatic tissue are taken from different areas of the prostate with a needle. The doctor may use an ultrasound to view the prostate and guide the needle during the biopsy. Ultrasounds cannot be used alone to tell if cancer is present.  Once removed the tissue is viewed under a microscope by a pathologist and evaluated for the presence of cancer cells. A “positive biopsy” means cancer is present in the prostate.  The pathologist examining the tissue will assign a “grade” to the tumor. The grade describes how fast or slow the tumor is likely to grow. There are different ways the grade of a tumor can be determined, however the common way is what is known as a “Gleason Score”.  Gleason Scores range from 2-10, the lower the number the less aggressive the tumor is likely to be.

The next step in evaluating the cancer is to obtain the “Stage” (or extent) of the disease. The Stage is based on the size of the tumor, whether the cancer has spread outside the prostate, and if so to what regions or organs.  The stages range from 1 to 4, 1 indicating the cancer is likely still localized within the prostate and 4 indicating the cancer has possibly spread (metastasized) outside the prostate to other parts of the body and possibly the lymph nodes.