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Is It Prostate Cancer?
Compared with most cancers, cancer of the prostate tends to grow slowly. Decades may pass from the time the earliest cell changes can be detected under a microscope until the cancer progresses enough to cause symptoms.
Like other cancers, prostate cancer can be diagnosed only by examining tissue under the microscope. When your doctor suspects prostate cancer-on the basis of your symptoms, or the results of a digital rectal exam (DRE), and/or a prostate-specific antigen (PSA) test-the diagnosis must be made by doing a biopsy.
Biopsy
To get a biopsy, you will go to a urologist and the procedure will be performed in the doctor's office. Using a transrectal ultrasound (TRUS) probe, the doctor first images your prostate, then inserts hollow biopsy needles into areas of the gland that feel or look suspicious. Bits of tissue are removed from each site through the needles; each snip causes a sharp sting. If a tissue sample is taken because of an elevated PSA test rather than a suspected abnormal area in the prostate gland, random tissue samples are often taken from six or more sectors of the prostate. In a so-called pattern biopsy, tissue samples are obtained from half a dozen or more carefully spaced sectors of your prostate gland; this helps establish the size and extent of any cancer. However, even when multiple samples are taken, biopsy can miss some cancers.
Your biopsy tissue samples are then examined by a pathologist, a doctor who studies and identifies the cell and tissue changes produced by disease.
Grading The Cancer
Healthy prostate cells are uniform in size and shape, neatly arranged in the patterns of a normal gland. As cancer grows, they lose their healthy look. They change from normal, well-differentiated tissues to more disorganized, poorly differentiated tissue. Eventually, a tumor develops.
If your biopsy shows the presence of prostate cancer, the pathologist assigns each tissue sample a grade, indicating how far the cells have traveled along the path from normal to abnormal. The grade offers a good clue to your tumor's behavior: a tumor with a low grade is likely to be slow-growing, while one with a high grade is more likely to grow aggressively or already to have spread outside the prostate (metastasized). The most widely used grading method for prostate cancer is known as the Gleason grading system (see Gleason Scores).
Tumor grade is useful as a predictor of outcome. In one analysis, 10 years after prostatectomy for localized cancer, prostate cancer had claimed the lives of 6 percent of the men whose cancers were well-differentiated compared with 20 percent of those with moderately differentiated cancers and 23 percent of those with poorly differentiated cancers. The chances of developing metastatic prostate cancer followed a similar pattern. Ten years after surgery, metastases had been diagnosed in 13 percent of the men with well-differentiated tumors, but in 32 percent of those with cancers that were moderately differentiated and 48 percent of those whose cancers were poorly differentiated.
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Gleason Scores The Gleason grading system assigns a grade to each of the two largest areas of cancer in the tissue samples. Grades range from 1 to 5, with 1 being the least aggressive and 5 the most aggressive. Grade 3 tumors, for example, seldom have metastases, but metastases are common with grade 4 or grade 5. The two grades are then added together to produce a Gleason score. A score of 2 to 4 is considered low grade; 5 through 7, intermediate grade; and 8 through 10, high grade. A tumor with a low Gleason score typically grows slowly enough that it may not pose a significant threat to the patient in his lifetime. |
Staging The Cancer
Once your cancer has been identified, the doctor wants to know how large it is and how far it has spread.
Depending on its size and spread, your doctor will stage your tumor. Information on your tumor stage, along with tumor grade and PSA level, is central to choosing your treatment and to monitoring its success.
Tumors stages are:
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Localized Stage I or A or TI: tumors that cannot be felt (nonpalpable). Stage II or B or T2: tumors that can be felt (palpable) but are confined to the prostate gland. Regional Stage III or C or T3: tumors that have grown through the prostate capsule, perhaps into the seminal vesicles. T4: tumors that have grown into nearby muscles and organs. Metastatic Stage IV or D and N+ or M+: tumors that have metastasized to the regional (pelvic) lymph nodes (N+) or more distant parts of the body (M+). |
Staging Systems One of two widely used staging systems, known as TNM, evaluates Tumor size and spread, cancer in the nearby lymph Nodes, and whether the cancer has established distant Metastases. The second system measures the same tumor characteristics, but uses an ABCD rating. |
Each of these stages is subdivided into more precise categories (see Staging Systems, above).
In 1990, two-thirds of newly diagnosed prostate cancers were Stages I or II (clinically localized). Slightly more than 10 percent were Stage III (regional), while about 20 percent were Stage IV (metastatic).
The main tests used for clinical staging of prostate cancer are DRE, PSA, and transrectal ultrasound (TRUS). Bone scans may be used when distant metastases are suspected.
The digital rectal exam (DRE), a procedure in which the doctor inserts a gloved finger into the rectum to examine the rectum and prostate to look for an irregular or abnormally firm area, helps to gauge tumor size, and it may show if the cancer has spread into nearby tissues.
PSA tests are playing an increasingly common role in cancer staging. Elevated PSA levels in the blood correlate roughly with the volume of cancer in the prostate, with the stage and grade of the tumor, and with the presence or absence of cancer metastases or growths in other tissues. (For more about PSA, see Resources section to order a copy of Understanding Prostate Changes: A Health Guide for All Men.)
Valuable information about tumor size and location can also be obtained from TRUS used to guide the biopsy in sampling abnormal areas of the prostate. TRUS uses an ultrasound probe inserted in the rectum to visualize the area on a screen.
The pathologist's evaluation of the biopsy samples also helps to establish the clinical stage (size and extent) of a cancer. The pathologist tallies how many of the tissue samples contain cancer, notes whether any of the samples are more than ha IF cancerous, and determines a Gleason score.
When clinical staging suggest that cancer has spread to the lymph nodes or beyond, radionuclide bone scans cart be used to look for metastases to bone, a common site of prostate cancer spread. However, research now shows that patients with PSA levels of 10 ng/ml or less, without bone pain, are so unlikely to have bone metastases - regardless of tumor stage or grade - that doctors often recommend that these patients can skip the bone scan.
Sophisticated imaging techniques such as computed tomography (CT) and magnetic resonance imaging (MRI) can also help uncover distant metastases. Like bone scans, however, such tests may be unnecessary for some men. Recent studies indicate that when prostate cancer is clinically localized - the situation for two-thirds of newly diagnosed cases - CT and MRl add little to the information available through DRE, PSA, and TRUS.
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Toward Better Testing The higher a man's PSA lavel, the more likely that cancer could be in the picture. During the screenings in men ages 50 or older, 85 of every 100 men will have normal PSA levels (4 ng/ml or below). Among the remaining 15 men, only 3 will have biopsies that show cancer. Some recent refinements designed to make PSA testing more accurate and more recise are under clinical study. For instance, PSA density relates a man's PSA level to the size of his prostate, which can be estimated through ultrasound. PSA velocity is based on changes in PSA levels over time; a sharp rise from a baseline level raises the suspicion of cancer. |
Lymph Nodes
When cancer occurs in the prostate, the gland's cells multiply abnormally and may eventually grow through the prostate capsule and invade nearby tissue. It may also spread to the lymph nodes of the pelvis, or it may spread throughout the body via the lymphatic system or the bloodstream.
Carefully removing and examining the lymph nodes-pelvic lymph node dissection-has traditionally been the final check to see if cancer has spread. It may be through "open" surgery or via laparoscopy, using a fiberoptic probe inserted through a small incision in the abdomen. When PSA level, tumor grade, and stage are evaluated, doctors may choose to bypass pelvic lymph node dissection. However, such clinical decisions may be revised to take into account new findings after surgery (prostatectomy). Pathologic staging judges tissues removed at prostatectomy. The pathologist looks for cancer in outer areas of the gland and at the surgical margins - the outermost cut edges of the surgical specimen.
Second Opinions
Once you receive your doctor's opinion about what treatments you need, it may be helpful to get more advice before you make up your mind. Other doctors' opinions can help you make one of the most important decisions of your life. Getting another doctor's advice is normal medical practice, and your doctor can help you with this effort. Many health insurance companies require and will pay for other opinions. Another opinion can help you:
(See Clinical Trials)
You may also consider contacting the prostate cancer support group in your area. Talking with other men who have experienced the different procedures available may help you to understand better the treatment options described by your doctor.
| << What is the Prostate Gland? | Making Treatment Choices >> |
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