Prostate Cancer Screening & Testing

Overview

This year in the United States, almost 230,000 men will be told that they have prostate cancer.¹ After a diagnosis of prostate cancer, a man and his family face several choices regarding treatment. Decisions involve many factors, personal as well as medical. Before making these decisions, it is very important to learn about all the options available. With this knowledge, a newly diagnosed prostate cancer patient can participate more confidently with his doctor in planning his individual treatment.

Screening means testing for cancer before you have any symptoms. A screening test can often help find cancer at an early stage. When found early, cancer is less likely to have spread and may be easier to treat. By the time symptoms appear, the cancer may have started to spread. Remember, even if your doctor suggests prostate cancer screening, this doesn't necessarily mean that you have cancer.²

Prostate-specific Antigen (PSA)

The 1980s witnessed the discovery of the blood test for Prostate Specific Antigen (PSA). Testing a blood sample for the amount of PSA now plays an important part in the early detection of prostate cancer. If an abnormally high level of PSA is detected in the blood, prostate cancer is a possibility. However, a high PSA score does not always indicate cancer and can be caused by other prostate diseases such as benign prostatic hypertrophy (BPH) or prostatitis (inflamed prostate).

Prostate-specific antigen (PSA) is a substance made by the normal prostate gland. Although PSA is mostly found in semen, a small amount is also present in the blood. Most men have levels under 4 nanograms per milliliter (ng/mL) of blood. When prostate cancer develops, the PSA level usually goes above 4.³ If your level is above 4 but less than 10, you have about a 25% chance of having prostate cancer. If it goes above 10, your chance of having prostate cancer is over 50% and increases as your PSA level increases.⁴

Your PSA will also normally go up slowly as you age, even if you have no prostate abnormality. Ejaculation can cause a temporary increase in blood PSA levels, so some doctors will suggest that men abstain from ejaculation for 2 days before testing. Several medicines and herbal preparations can lower blood PSA levels. You should tell your doctor if you are taking finasteride (Proscar or Propecia).⁵

If your PSA level is high, your doctor may recommend a prostate biopsy to determine if you have cancer. Before doing that, however, there are some new types of PSA tests that might help determine if you need a prostate biopsy. Not all doctors agree on how to use these additional PSA tests. If your PSA test result is not normal, ask your doctor to discuss your cancer risk and your need for further tests.⁶

The FDA has also approved the PSA test to monitor patients with a history of prostate cancer to see if the cancer has come back (recurred). An elevated PSA level in a patient with a history of prostate cancer does not always mean the cancer has come back. A man should discuss an elevated PSA level with his doctor.⁷

Digital Rectal Exam (DRE)

During this examination, a doctor inserts a gloved, lubricated finger into the rectum to feel for any irregular or abnormally firm area that might be a cancer. The prostate gland is located just in front of the rectum, and most cancers begin in the back part of the gland that can be reached by a rectal exam. While it is uncomfortable, the exam causes no pain and only takes a short time.⁸

Although DRE is less effective than the PSA blood test in finding prostate cancer, it can sometimes find cancers in men with normal PSA levels. For this reason, the American Cancer Society guidelines recommend the use of both the DRE and PSA blood test for early prostate cancer detection. The DRE is also used once a man is known to have prostate cancer to help determine if the cancer has spread beyond his prostate gland and to detect cancer that has come back after treatment.⁹

Biopsy

A core needle biopsy is the main method used to diagnose prostate cancer. A biopsy is a procedure in which a sample of tissue is removed and then examined under a microscope. The doctor will use transrectal ultrasound (TRUS) for guidance and insert a narrow needle through the wall of your rectum into several areas of your prostate gland. The needle then removes a cylinder of tissue, usually about 1/2-inch long and 1/16-inch across, that is sent to the laboratory to see if cancer is present.¹⁰

Though the procedure sounds painful, it typically causes little discomfort because a special instrument called a biopsy gun inserts and removes the needle in a fraction of a second. Also the doctor can numb the area with a local anesthetic. The procedure takes about 15 minutes and is usually done in the doctor's office. Several biopsy samples are often taken from different areas of the prostate. Anywhere from 6 to 13 samples are usually needed to determine if cancer is present and how much of the gland is affected, but as many as 18 samples may be taken from some patients. You may want to discuss the number of biopsies to be taken with your doctor before the procedure starts.¹¹

Unfortunately, even when taking more samples, biopsies can occasionally miss detecting cancer. This is known as a "false negative" result. If your doctor still strongly suspects you may have prostate cancer (due to a very high PSA level, for example) a repeat biopsy may be needed to help rule this out.¹²

Some doctors will perform the biopsy through the perineum, the skin between the rectum and the scrotum. The doctor will place his or her finger in your rectum to feel the prostate and then insert the biopsy needle through a small incision in the skin of the perineum. The doctor will also use a local anesthetic to numb the area.Your biopsy sample will then be sent to a pathology laboratory. There, the pathologist (a doctor who specializes in diagnosing disease in tissue samples) will determine if there are cancer cells in your biopsy sample by examining it under the microscope. This analysis usually takes 1 to 3 days. If cancer is present, the pathologist will also assign it a grade.¹³

Grading the Cancer

Based on the microscopic examination of tumor tissue, pathologists may describe it as a low-, medium-, or high-grade cancer. One way of grading prostate cancer is the Gleason system, which uses scores of 2 through 10. The pathologist studies samples of prostate tissue and grades the appearance of the tumor tissues on a scale of 1 to 5 to indicate how different they are from normal prostate tissue. The two most common grade patterns – or the most common and the most abnormal – grade patterns are added together to make a Gleason score. The higher the score, the higher the grade of the tumor. High-grade tumors (Gleason score 7-10) can grow more quickly and are more likely to spread than lower-grade tumors.¹⁴