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How is an Examination (Digital Rectal Exam/DRE) performed:

The digital rectal exam is the simplest way to detect physical abnormalities in the prostate gland that may suggest the presence of cancer. The DRE is also used to estimate the volume of the prostate and can sometimes help determine the extent of the cancer.

Unlike the standard approach taken by most urologists, where the patient is asked to bend over a table for the digital exam, we perform digital examinations of the prostate with the patient in the dorsal lithotomy position – lying on his back with his legs drawn up (much like the position a woman is in for a pap smear – see illustration). This position causes the prostate gland to literally fall naturally against the physician’s fingers, allowing for a more complete and relaxed examination of the gland.

To perform the rectal exam, the doctor feels the gland by placing a lubricated, gloved finger inside the rectum against the prostate. When done properly, the test is not as discomforting as it might sound. Most cancers are located in the back of the prostate, and some of these cancers that have grown at the edge of the gland can be felt as a lump or hard nodule. Depending on the size, shape and location of the lump, it is sometimes possible to determine with a DRE if the cancer is likely to have spread beyond the prostate capsule. With the DRE, the doctor is able to evaluate the major portions of the gland’s anatomy: the right and left sides or lobes; the upper portion of the base of the gland the middle portions of the gland’s anatomy; the right and left sides or lobes; the middle portion of the gland; and lower portion or apex. However, not all surfaces of the gland can be reached by the DRE.

Unfortunately, the DRE is often not accurate. Many prostate cancers do not protrude against the back of the gland; they are not palpable and cannot be detected with the DRE. A tumor at the front of the prostate cannot be felt through the rectum. In addition, the test is subjective and depends on the skill of the doctor, providing at best only an estimate of the extent of the disease. Many surgical studies have shown that more than 50% of cancers that appear to be confined to the gland will later be found to have spread beyond the gland. However, DRE is important as it is sometimes able to reveal tumors that would have been missed by PSA blood test alone.

What is the PSA Test

The PSA test was developed during the late 1970’s by research scientists at Roswell Park Memorial Hospital in Buffalo, New York. The PSA is a blood test that measures the amount of prostate specific antigen (PSA) present in the body. Produced almost exclusively by the prostate gland, PSA is an enzyme, typically present in only minute quantities, secreted into the bloodstream from blood vessels inside the prostate.

PSA secretions originate from cells in the lining of the prostate gland. When prostate cancer is present, additional PSA is usually produced. This extra PSA can be detected and measured in the blood through a simple laboratory test, which can be ordered by any primary-care physician. Test results are usually available in several days, or possibly longer depending on the assay used.

Because cancerous cells readily leak PSA into the surrounding body tissue, an elevated PSA is a possible indicator of the presence of prostate cancer. However, other conditions can also cause an elevated PSA. The most common is the enlargement of the prostate gland that occurs with BPH (benign prostate hypertropy). Infections and traumas such as a biopsy or even an overly vigorous digital rectal exam can sometimes increase PSA levels. Ejaculation (orgasm) can elevate PSA for as long as 48 hours.

As a diagnostic tool, the PSA test has its limitations, and is usually combined with the DRE and other tests. Some men with seemingly normal PSA values turn out to have prostate cancer that may be detected with the DRE or another diagnostic test. A more aggressive cancer may sometimes be associated with a palpable tumor (a least a billion cells) found by DRE and normal or even low PSA.

How Are PSA Results Reported

Standard PSA test results are reported in nanograms per milliliter (ng/ml), with a normal range of approximately 0-4 ng/ml. For the sake of simplicity, the units of measure will not be included in the remainder of this discussion. The normal range of PSA values must be adjusted slightly to account for differences in age and race. As men get older, the normal PSA range slowly increases. This normal range is generally lower for Caucasion males than for Asians and Afro-Americans.

Regardless of age and race factors, PSA levels greater than 10 are most often an accurate indicator of cancer. As many as 80 percent of men with this an elevated PSA reading (and positive digital rectal exam) have been shown to have prostate cancer. Approximately 25 percent of those patients with a PSA between 4 and 10 turn out to have cancer, as confirmed by standard prostate biopsies. The accuracy of the PSA test is significantly improved when it is combined with the digital rectal exam. The PSA can detect twice as many cancers as the DRE alone; however, the DRE spots some cancers that may be missed by the PSA.

It should be stressed that the PSA test is not conclusive by itself in diagnosing prostate cancer. No treatment decision should ever be made on the basis of the PSA value by itself; however, an elevated PSA reading may suggest the need for further laboratory tests. A biopsy of the prostate gland is always necessary to confirm the presence of cancer.

Because the PSA test is not completely reliable as far as its predictive value, a patient with a high PSA level may not necessarily have cancer and a patient with a very low PSA may not be cancer free. In fact, high grade, more aggressive cancers can lose their resemblance to prostate cells altogether and may not even produce PSA. The PSA provides only a statistical approximation, and there are often exceptions. PSA results are discussed in terms of probabilities, the likelihood of prostate cancer being present, and the likelihood that it may have spread beyond the prostate gland.

What do I do if I have a rising PSA with a negative Biopsy(-s)

Unfortunately, some men find themselves in the frustrating and frightening position of having a continuing increasing PSA with negative biopsy results. Some of these men believe they have cancer and that the biopsy needle has simply missed it. Others are uncertain what to think. Most are confused how to proceed or what to do next. If your doctor is attempting to distinguish between prostate cancer and BPH, there are several additional factors relating to PSA that can be considered:

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