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Prostate Cancer Profiler Main
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This section includes: Screening Screening tests are available that can detect prostate cancer even when there may be no symptoms. The American Cancer Society, the American Urological Association, and the National Comprehensive Cancer Network recommend that healthcare providers offer men who are 50 years or older the option of testing for early detection of prostate cancer. Prostate cancer usually begins to grow in the area of the prostate that faces the rectum (peripheral zone). Because of this location, the use of a digital rectal exam (DRE), whereby a physician inserts a gloved, lubricated finger in the rectum, can sometimes allow the physician to feel a cancer. PSA Blood Test Cancers are usually first suspected through a digital rectal exam or through a blood test that measures the amount of prostate specific antigen (PSA), a protein produced only by prostate cells. PSA results are reported as nanograms per milliliter or ng/ml. The PSA level may rise in men who have BPH, an infection in the prostate, or prostate cancer. A level less than 4 ng/ml is usually considered normal, values between 4 and 10 are borderline, and above 10 ng/ml is high. Normal levels, however, vary according to age and race. The prostate specific antigen (PSA) blood test is a valuable tool for evaluating the extent of disease, but as a single tool is only partially accurate in predicting the presence and location of the cancer. Most men with prostate cancer and a PSA less than 10 ng/ml have organ-confined disease that can be treated with local pelvic area regimens. Those who have a PSA greater than 10 ng/ml are less likely to have prostate cancer within the area of local treatment. Prostate cancer can only be confirmed through a biopsy. A biopsy is a surgical procedure that removes a sample of cell tissue for examination under a microscope by a pathologist. Biopsies of the prostate gland are performed via ultrasound guidance through the rectal wall. Usually three to five biopsies per side of the prostate are taken. Complications of biopsy may include pain with urination, blood in the urine or pelvic pain. If cancer is found, the pathologist describes its characteristics, or the changes in the cancer cells that range from fairly normal looking to very abnormal looking using a grading system called the Gleason grading system. Gleason Grading System The Gleason grading system uses a five-point scale to rate how different the cancer cells look from normal prostate cells. If the cells look similar to normal cells they are called "well-differentiated" and given a low grade, such as 1. As the cells begin to look less and less like normal cells, they are given an increasing grade, up to 5, or "poorly-differentiated." The pathologist looks for the most predominant types of cells and grades them and then looks for the next most predominant type of cells and grades those. The most predominant cell type grade is called the primary Gleason grade, and the second most predominant is called the secondary Gleason grade. The two grades are added together to create a score called the Gleason score. The Gleason score can range from 2 (primary grade 1 plus secondary grade 1) to 10 (primary grade 5 plus secondary grade 5). Most patients have Gleason scores of 5 or 6. The higher the Gleason score, the more likely that the cancer will grow and spread rapidly. The Gleason score only partially predicts for the extent of disease. Clinical Stage Staging is the process of determining how far the cancer has spread so an appropriate treatment can be recommended. The cancer stage is a critical factor in selecting treatment options and predicting outcomes (likelihood of progression and survival). There are many different ways to determine the extent of the cancer. The simplest of these is the clinical stage as determined by the digital rectal exam. This clinical stage is not influenced by the PSA or biopsy results. The clinical stage is assigned to the patient after the initial digital rectal exam and does not usually change unless the bone scan is positive. Newer clinical staging systems include ultrasound or magnetic resonance imaging (MRI) results, however, because these are relatively new systems, there are no long-term studies evaluating results of these tools. As a result patients should be cautious about applying them to their own situation. A common error in clinical staging is to use the results of the biopsy. Biopsy results do not affect the clinical stage. For example a patient with no palpable tumor (T1c) does not become a T2b because tumor was found on biopsy to be in both lobes. Clinical stage is the stage reported by most studies and is the criteria used for the initial treatment decision. Pathological Stage The clinical stage is rarely used as the sole method of determining the extent of the cancer. Studies have demonstrated that the clinical staging by DRE alone is an inaccurate method to determine the extent of disease. Additional information about the cancer is provided after surgery to remove the prostate (prostatectomy) by the pathologist who examines under a microscope the prostate gland, seminal vesicles (fluid sacs attached to the prostate) and, in some cases, nearby lymph nodes. This is called the pathological stage and is used to determine the need for additional treatment after surgery. A cancer found completely inside the prostate is called organ-confined. A cancer that has spread to the seminal vesicles is considered to have seminal vesicle involvement. If a cancer breaks through the wall of the prostate, called the prostatic capsule, then the cancer is said to have extraprostatic extension or extracapsular penetration. Patients with extracapsular penetration of only a short distance may be candidates for additional therapy in the pelvic area (local therapy). Prostate cancer cells can also invade nearby lymph nodes. This cancer is said to have lymph node involvement. Seminal vesicle and lymph node involvement is associated with less favorable outcomes. Prostate cancer usually first spreads to the bones and rarely involves other organs. Cancer that has spread to the bones or other organs is called metastatic and has the poorest outcomes. Better Staging Technology The ability of individual tests to predict for the extent of cancer is limited. In an attempt to improve the accuracy of tumor staging, clinical experts are attempting to combine the individual tests to create a better "model" for predicting stage. The idea is to create a single score combining the results of several individual tests, such as Gleason score, clinical stage and PSA. The results of these new models have been shown to improve the accuracy of staging prostate cancer. The Gleason score, Grade and PSA are the most powerful predictors for extent of disease. Combined, these factors can more accurately predict the extent of the disease. Useful tools have been devised such as the Partin tables, which combine these factors to give the physician and patient the ability to estimate the likelihood that the cancer has spread beyond the prostate gland. When you use the Prostate Cancer Profiler, your results will be evaluated by the Partin table method and are described in step three of the Prostate Cancer Profiler™ (the Staging Report). Transrectal Ultrasound (TRUS) TRUS plays an important role in the diagnosis and treatment of prostate cancer. TRUS uses sound waves to create images on a video screen. A small probe is inserted into the rectum. Sound waves from the probe are then bounced off the prostate and an image is formed on a monitor that the physician can view. TRUS images are unreliable for accurately defining a cancer or its extent. TRUS is extremely useful, however, and performed almost universally for guiding needles into the prostate during a biopsy and for prostate seed implants (brachytherapy planning and treatment). Computerized Tomography (CT Scan) The CT or CAT scan uses a rotating x-ray beam to create pictures of your body from different angles. The CT scans are rarely useful to view the prostate gland, as they are unreliable for determining the extent of the cancer in the prostate. CT scans may be used to view lymph nodes to which the cancer may have spread. Research studies of the ability of CT scans to accurately identify cancers in the lymph nodes have produced variable results ranging from 25 percent to more than 80 percent. Magnetic Resonance Imaging (MRI) MRI is similar to a CT scan except that it uses magnetic fields instead of x-rays to create internal pictures of your body. MRI is very good at imaging the prostate but has limited usefulness for differentiating benign from cancerous areas. The overall accuracy of MRI scans is about 60 percent. Standard MRI, therefore, has limited usefulness for determining the extent of disease. There is a new MRI technology that uses a probe, called a coil, inserted in the rectum to create an image of the prostate. This technique, which has not been widely studied, has been shown to be 82 percent accurate for predicting whether the cancer has moved beyond the walls of the prostate and nearly 97 percent accurate for predicting whether it has spread to the seminal vesicles. Studies are underway to determine the usefulness of this type of MRI to predict the extent of disease. At present it is still considered experimental. Bone Scan A test called a bone scan is performed to see if the cancer cells have spread to the bone. For this test, the radiology technician injects a small amount of radioactive material into the patient's bloodstream and the patient returns later for the scan. The radioactive material collects in the area where there are bone-activating cells and a scanner will pinpoint the areas of abnormality that can be further evaluated to determine if cancer invasion is the cause. Staging Terminology In 1992, the American Joint Committee on Cancer (AJCC) and the International Union Against Cancer adopted a new staging terminology called the TNM system. The T represents information about the primary Tumor, such as its size and how it was detected. N indicates lymph node involvement and M indicates whether the cancer has spread or metastasized. The table below describes TNM staging for prostate cancer. Stage Sub-Stage Definition
This content is reviewed regularly. Last Updated 6/6/2007
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