The Early Detection of Prostate Cancer

Early detection is especially important in prostate cancer, because when this form of cancer is diagnosed early, the chances for a cure are greatly increased.

The digital rectal examination is a simple procedure where the physician inserts a lubricated gloved finger into the man’s rectum. This examination can help the doctor detect a mass. To confirm the presence of cancer, the urologist will perform a biopsy, which involves obtaining a small sample of the prostate to determine whether it contains cancer cells. In order to tell if the cancer has spread outside the prostate, several tests are useful for detecting and staging prostate cancer. Not all of these tests are needed in all men.

The prostate-specific antigen (PSA) test is a blood test that can indicate the presence of prostate cancer. However, the PSA test is sometimes difficult to interpret because PSA is produced by both normal and cancerous prostate cells.In general, the higher the PSA level, the greater the chance that the cancer has spread beyond the prostate.

Ultrasound provides an image of the prostate that the doctor can use to measure the size of the prostate, look for
cancerous tissue, and calculate the PSA density (the PSA level divided by the size of the prostate). A needle biopsy
of the prostate is usually performed under ultrasound guidance.

A prostate biopsy analysis of the tissue gives important information about the cancer. The tumor grade is determined by examining the tissue under a microscope to measure the amount of disorganization of cells. A Gleason grade, which ranges from 2 to 10, is one scale that can be used to estimate the tumor's growth rate. Generally, the lower the grade, the slower the cancer grows. Most localized cancers of the prostate are of an intermediate grade, (Gleason grades 4, 5 or 6). The Gleason grades for the two most prominent groups of cells is called the Gleason Score.

It is important to understand that at least two physicians work with you through the diagnosis phase, one who will analyze your prostate disease (the pathologist) and one who will detect and treat it (usually a urologist and/or radiation oncologist). At present, the only definitive method for determining the presence or absence of cancer in a prostate gland is by the analysis and interpretation of tissue samples by a pathologist. The interpretation of tissue samples is a result of the pathologist’s medical judgment, and legitimate differences of opinion can exist. A second opinion might be valuable in certain circumstances.

A bone scan produces a nuclear image of the bones. this test, which may detect the spread of cancer to the bones, may not be necessary in all patients, especially those with small cancers, low PSA levels and low Gleason grades.

Computed tomographic scan (CT scan) is an X-ray procedure that produces cross-sectional images of the body. The CT scan may help detect lymph nodes in the pelvis that are enlarged because of cancer. Generally, a CT scan is used only if the cancer is large, of a high grade, or associated with a very high PSA level.

The lymph nodes in the pelvis usually are the first place that cancer spreads from the prostate. The doctor can make a rough estimate of how likely it is that cancer has spread to the lymph nodes. This estimate is based on the cancer's size in the prostate and on results of the biopsy. A high PSA level also may indicate that the cancer has entered the lymph nodes. However, cancer in the pelvic lymph nodes often is microscopic. If there is a high risk that the cancer has spread to the lymph nodes, the doctor may recommend that they be surgically removed and examined under a microscope. Because there are many lymph nodes elsewhere in the body, the loss of some of the pelvic lymph nodes does not usually cause problems.

An antibody that binds to the prostate specific membrane antigen (PSMA) may be able to detect cancer that has spread beyond the prostate and into soft tissue. Many prostate cancer cells produce the PSMA protein, which stays attached to the cancer cells. During the scan an antibody, with radioactive material attached, is injected into a vein. The antibody then circulates throughout the body, but only binds where it finds the PSMA protein. After four or five days, the antibody that does not bind to the PSMA is cleared from the body. Ideally, most of the remaining antibody will be bound to the prostate cells bearing the PSMA. In disease recurrence following prostatectomy, this type of test may indicate whether the cancer is limited to the prostate and may be useful in identifying patients most likely to benefit from salvage local therapy. Unfortunately, there are limitations to this type of scan, because it may be difficult to interpret. Currently, the only commercially available scan of this type is ProstaScint.