Prostate Cancer: Detecting

by Food and Drug Administration (FDA)

Russ Ingram didn't sense pending calamity when he reported for a company physical seven years ago. After all, he was in good shape and, at 39, still very much a robust young man with no signs of health problems.

During part of the exam, however, the doctor noticed that Ingram's prostate was enlarged. While this can indicate a tumor, often it signals a common benign prostate condition, usually in men much older than Ingram. But a visit to a urologist produced the grim news that his condition was not benign. He had prostate cancer.

"I was devastated," says Ingram. "Due to my age, I didn't think there was anything to worry about. It caught me totally off guard. I didn't even know where the prostate was."

To be sure, Ingram's case is not typical. His age at diagnosis placed him well outside the primary risk group for prostate cancer. Statistically, at least 80 percent of prostate cancers occur in men over 65. In fact, men in their 30s are not usually tested for prostate cancer in a physical and Ingram says it was just "a fluke" that the doctor discovered the enlarged prostate.

While the disease can strike any man, younger men at increased risk include African Americans, who have double the risk and death rate of white men and often are stricken before age 50. Men with a family link to prostate cancer through brothers or fathers also are at a greater risk of getting the disease before 50.

The American Cancer Society estimates that in the year 2000, nearly 180,400 American men will be diagnosed with prostate cancer and 31,900 will die from the disease. (In comparison, 1998 estimates for lung cancer in men are 171,500 cases and 160,100 deaths; for colorectal cancer, the estimates are 131,600 cases and 56,000 deaths.) Despite the bleak numbers, 89 percent of men diagnosed with the disease will survive at least five years and 63 percent will survive at least 10 years, the society says. These rates are partly due to improved screening tests and diagnostics the Food and Drug Administration has approved that discover cancer in early stages. Also, prostate cancer is very slow-growing in some men, who may die of some other cause before the disease takes its toll.

Detecting Prostate Cancer

The prostate is a male sex gland, about the size of a walnut. It produces a thick fluid that helps propel sperm through the urethra and out of the penis during sex. Because the prostate is just below the bladder and directly in front of the rectum, a doctor can check the size and condition of the gland by inserting a rubber-gloved finger into the rectum. This digital rectal exam (DRE) has for years been the gold standard for detecting prostate cancer as well as the noncancerous disorder benign prostatic hyperplasia (see "Noncancerous Prostate Disorder").

In 1985, FDA approved the first test for monitoring blood levels of a substance called prostate specific antigen (PSA), which, when elevated, can indicate cancer presence. Several companies now have approved PSA tests, which, experts say, have revolutionized the screening and monitoring of patients.

PSA is an ideal marker for prostate cancer because it is basically restricted to prostate cells. A healthy prostate will produce a stable amount — typically below 4 nanograms per milliliter, or a PSA reading of "4" or less — whereas cancer cells produce escalating amounts that correspond with the severity of the cancer. A level between 4 and 10 may raise a doctor's suspicion that a patient has prostate cancer, while amounts above 50 may show that the tumor has spread elsewhere in the body.

Most PSA tests measure "total PSA," or the amount that is bound to blood proteins. In 1998, FDA approved the Tandem R test, which measures not only total PSA but another component called "free PSA," which floats unbound in the blood. Comparing the two helps doctors rule out cancer in men whose PSA is mildly elevated from other causes. A 1995 study in the Journal of the American Medical Association showed that the free PSA test can reduce unnecessary prostate biopsies by 20 percent in patients with a PSA between 4 and 10.

The availability of increasingly sensitive testing devices has created a debate over when men should be tested for prostate cancer, how often, and whether men under 50 with no symptoms should be routinely screened. Opponents say mass screening would be expensive, and the verdict is still out on whether early detection can curb the disease's mortality rate. But proponents say early detection is the closest thing currently to a cure and that it can save lives. The American Cancer Society and the American Urological Association recommend annual PSA tests — along with the digital exam — for all men over 50 and for high-risk men over 40.

The PSA test, though a powerful tool, "is not perfect," says Jean Fourcroy, M.D., a urologist and medical officer in FDA's Center for Devices and Radiological Health. Besides being thrown off by noncancerous conditions, the tests can vary between manufacturers. "Patients and physicians should use the same brand of PSA test throughout monitoring because of these possible variations," Fourcroy says.

When PSA or digital tests indicate a strong likelihood that cancer is present, doctors usually order a transrectal ultrasound (TRUS), a probe inserted into the rectum that uses sound waves to "map" the prostate and show any suspicious areas. Doctors then may take biopsies of various sectors of the prostate using tiny hollow needles inserted through the rectum. Biopsies are the only definitive way to determine if prostate cancer is present.

If the biopsy indicates cancer, the doctor then "stages" the tumor based on which biopsy specimens contain cancer, the extent of cancer, and the location of cancer in the specimens. Staging also depends on the extent and location of cancer outside the confines of the prostate.

Another important measure, the Gleason score, gauges the probable aggressiveness of the tumor based on the cellular differences of the cancer. Tumor cells that look similar to normal cells tend to be less aggressive, while those distributed randomly with uneven edges are likely to spread rapidly. Two numbers, each from 1 to 5, are assigned. The higher the numbers when the two are added, the more aggressive the tumor is likely to be.

Doctors also examine the ploidy, or number of sets of chromosomes in a cancer cell. Diploid cells, for example, have a complete set of normally paired chromosomes, and tend to grow slowly and respond well to therapy.

Recently, some doctors have begun using Partin Tables, a scoring method developed at Johns Hopkins University that uses PSA, Gleason number, and staging to predict if the disease is confined or has spread to other sites. Doctors also can determine cancer spread with imaging techniques such as bone scans and computerized tomography (CT) scans.

About the Author

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