What Is Prostate Cancer?
The exact cause of prostate cancer is unknown. We do know that prostate cancer begins when a group of cancerous cells (a tumor) forms within the prostate. The human body is made up of billions of cells. Normally, cells function for a while, then die, and are replaced in an orderly fashion. This results in an appropriate number of cells that are organized by the body to perform specific functions.
Occasionally, however, cells are replaced in an uncontrolled way and are unable to be organized by the body for normal function. An abnormal growth of cells is called a tumor. There are two kinds of tumors: malignant tumors (cancers) and benign tumors (non cancerous growths).
Because of their increasing size, benign tumors squeeze surrounding parts of the body and expand into nearby areas. This can cause pain and interfere with normal function, but it is seldom life threatening.
Cancerous tumors can cause pain and interfere with normal function, but they also can cause other systems in the body to act abnormally. This type of tumor can invade nearby groups of cells or tissues, crowding out and destroying normal cells. Cancer cells also may break away from tumors and enter body fluids, which allow such cells to spread to other parts of the body. This process is called metastasis. Cancerous tumors that spread to other parts of the body (metastic cancers) can threaten a persons life.
The body fluids that can carry cancer cells are the blood and the lymph. Most people know about blood and blood vessels but may not be familiar with lymph. The lymph is a nearly clear fluid that drains waste from cells. This fluid travels through vessels and small bean-shaped structures called lymph nodes. One function of lymph nodes is to filter unwanted substances, such as cancer cells, out of the fluid. If there are too many cancer cells, however, the nodes cannot remove all of them.
How Is Prostate Cancer Diagnosed?
The cause of prostate cancer is unknown. It is known, however, that the growth of cancer cells in the prostate, like that of normal prostate cells, is stimulated by male hormones, especially testosterone.
Compared with other types of cancer, prostate cancer is relatively slow growing. In fact, many men with prostate cancer will not die from it but with it. As a man gets older, his risk of developing prostate cancer increases.
A man may live for many years without ever having the cancer discovered. As the cancer grows, however, the prostate may eventually squeeze the urethra, which it surrounds. Then symptoms such as difficulty in urinating may develop. This is usually the first symptom of prostate cancer. (It is important to note, however, that difficulty in urinating can be caused by other, noncancerous conditions of the prostate and does not always mean that prostate cancer is present.)
With or without symptoms, a growing cancer also can begin to attack cells close to the prostate. At the same time, cells can break of from the cancer and spread to other parts of the body. Sites where prostate cancer tends to spread are the lymph nodes, the lungs, and various bones, especially the bones of the hip and lower back.
Like the main prostate tumor, tumors that have spread to other areas of the body can expand and squeeze other body parts. When prostate cancer spreads, the most common symptom is bone pain. The American Cancer Society (ACS) has developed guidelines to help doctors detect prostate cancer during its early stages. The ACS has recently revised these guidelines to reflect new scientific literature. The new guidelines recognize that prostate cancer screening, including a Digital Rectal Examination (DRE) and a yearly test to measure prostate-specific antigen (PSA) in the blood, should be offered to the general male population 50 years of age and older. In addition males with two or more first-degree relatives affected by the disease, or those of African-American descent, should consider starting prostate cancer screenings at an earlier age.
You and your physician can discuss ACS guidelines together and determine if screening is right for you and, if so, when you should begin.
PSA is a substance produced by both normal and cancerous prostate cells. When prostate cancer grows or when other prostate diseases are present, the amount of PSA in the blood often increases. New ACS guidelines advise men with high PSA results to have a biopsy. This will help determine if cancer is actually present. A PSA test is generally said to be in the normal range when it is reported to be between 0 and 4 nanograms per milliliter, sometimes abbreviated as ng/ml on the lab report. If the results are in the high range (reported to be greater than 10 ng/ml), then your physician may suggest a biopsy.
Sometimes, PSA results are in the borderline high range. This occurs when the results are measured to be between 4 and 10 ng/ml. PSA test results in this range can be confusing and do not always mean that cancer is present. Certain other conditions, such as benign prostatic hyperplasia (also called BPH-a type of non cancerous prostate enlargement) and prostatitis (inflammation of the prostate), may cause an abnormal PSA result. If your PSA test results are borderline high, but your DRE results are normal, then your doctor may decide to recommend a Transrectal Ultrasound (TRUS). This is a test that may help to find abnormal areas that may require a biopsy. On the other hand, if the results of the TRUS are normal, you may be able to wait and repeat the PSA test a few months later and have biopsy then if needed. New ACS guidelines suggest a biopsy for any man with abnormal DRE results, even if the PSA is normal.
Because borderline PSA tests can be confusing, your physician may advise you to consider having one or more of the newer PSA tests. These are described below:
Percent Free-PSA Ratio – A blood test that measures how much PSA circulates by itself (unbound) in the blood and how much is bound together with other blood proteins. If PSA results are borderline and percent free-PSA ratio is low (25% or less), the prostate cancer is more likely to be present. If this is the case, a biopsy may be needed. If the results of the percent free-PSA ratio are normal, even with a borderline PSA, you may be able to avoid a biopsy.
Age-Specific PSA Reference Ranges – This is another way of looking at PSA. Higher PSA levels are normally seen in older men more often than in younger men, even without cancer. An age-specific PSA reference range compares the results of men in the same age group. If a man’s PSA levels are high compared to his own age group, then there is a higher chance that prostate cancer could be present. In older men with borderline PSA results, this comparison can be more confusing than useful. As a result, age-specific PSA reference ranges are not routinely done.
If you have had your PSA measured and also have had a TRUS, the PSA density (PSAD) can be determined. To determine what the PSAD is, your physician will divide the PSA number result by the size, or volume, of the prostate (from the TRUS results). The chance that prostate cancer is present is greater with a high PSAD.
PSA Velocity – This will show how quickly the PSA level rises over a period of time. Two or more PSA tests will be required, often over several months of time. Although PSA velocity may be useful in helping your doctor better interpret borderline PSA results, it is not really used to diagnose prostate cancer. Instead, it is used more as a tool to keep track of how your PSA levels compare over a period of time. PSA often rises as part of the natural aging process; an increase in the PSA from time to time does not necessarily indicate that prostate cancer is present. On the other hand, if PSA increases too quickly (as determined by your physician), prostate cancer is a possibility.
Newer PSA tests can be useful, but they are still too new for physicians to agree on when and how they should be used. If your PSA is borderline or abnormal, your doctor can help you determine which tests, if any, are right for you. To detect prostate cancer and to determine the size and extent of the spread-or stage-of the disease, your doctor may perform tests that involve feeling the prostate, looking at internal parts of the body, measuring the levels of substances in the blood, and examining samples of prostate cells.