Should you get a PSA test?

by Howard Bell

Walter Petersen gets a digital rectal exam and a PSA test for prostate cancer as part of his yearly physical. For 10 years, he scored a 2, which is normal. But in the spring of 1998, his PSA level shot up to 4.2. Three months later, it was 6.2. Time for a biopsy, his doctor told him. The biopsy showed he had prostate cancer. Today, after undergoing radioactive seed implant treatment, Mr. Petersen is cancer-free.

"My digital rectal exam was normal and I had no symptoms," says Petersen. "If it wasn't for the PSA test, no one would have known I had cancer."

Stories like Petersen's make it hard to understand why doctors disagree about how useful the prostate-specific antigen (PSA) test really is. Some doctors believe it detects prostate cancer early enough to reduce deaths and prolong life expectancies. Others say there's no proof it does either.

The PSA test is a simple blood test that measures the levels of prostate-specific antigen in your blood. It's usually done during a routine physical. All prostates? healthy and unhealthy? produce PSA, so it's normal to have some PSA in your blood. And it's normal for that level to rise as you get older. But PSA levels that rise too high or too fast may indicate prostate cancer.

Readings of 0-4 are considered normal unless the level is rising rapidly, as was the case with Mr. Petersen. Levels of 5-9 may be cause for concern, especially if you're under the age of 60. Levels of 10 or more are usually a concern at any age up until age 70, beyond which studies show you don't gain any life expectancy by treating the cancer.

A high blood PSA level may mean you have prostate cancer. Then again, you may not. Therein lies one problem with the test. It's great at measuring high levels of PSA in your blood, but not as good at telling you why it's high. You may have a prostate infection (prostatitis) or benign enlargement of the prostate (benign prostatic hyperplasia, or BPH). Levels also go up temporarily after sex, or after having a digital rectal exam.

Only 15-20% of men with high PSA levels have prostate cancer. The cancer rate is higher (40%) among men with PSAs greater than 10, but that means a lot of men with high PSA levels don't have cancer. In other words, the test produces a lot of what doctors call "false-positives," results that falsely indicate prostate cancer. "Some men have PSAs of 30," says, David Arvold, MD, an internist at St. Mary's/Duluth Clinic in Duluth, Minnesota, "but they don't have cancer."

The test also produces lots of "false-negatives," meaning some men with normal PSA levels may have prostate cancer. Most prostate cancers are slow-growing and may exist for decades before they are large enough to cause symptoms. Subsequent PSA tests may indicate a problem before the disease progresses significantly.

Say you have a PSA test and your levels are high. What should you do next?

You could go home and do nothing. Doctors call this "watchful waiting." But more likely, you'll proceed to the next level and get a biopsy of your prostate. If the biopsy is negative, that's good news, but a biopsy can miss the cancer because the samples analyzed came from a non-cancerous part of your prostate. So a second biopsy may be called for. A second negative biopsy is really great news. But what if it's positive?

If the cancer is aggressive, it should be treated, unless you're quite old. If it's not aggressive, your quality of life may be better if the cancer is left untreated. It's impossible for doctors to predict which cancers will blossom into life-threatening problems and which won't. Most do not. They just continue to grow slowly without any significant ill effects.

Some studies support Dr. Arvold's opinion that many men? perhaps even most men? would do better not to treat early prostate cancer because the side effects of treatment can be worse than the disease. Fifty percent of men who have their prostates removed become permanently impotent, according to research published in the Annals of Internal Medicine, and 20-30% have some permanent loss of bladder control.

Even external beam radiation treatment poses a 10% chance for permanent bowel problems. "If you treat with external beam radiation or surgically remove the prostate," says Dr. Arvold, "your likelihood for a diminished quality of life is high." Radioactive seed implants pose the lowest risk for complications, but less than half of the men with prostate cancer are eligible for this procedure, and although early results look promising, the jury is still out on how effectively this procedure prolongs your life.

Nationwide, 60% of all prostate cancers are now discovered before they spread outside the gland. "The test allows us to detect a cancer on average five years earlier," says Michael Blute, MD, a urologist at the Mayo Clinic in Rochester, Minnesota. "That translates into a better chance the cancer can be effectively treated."

The Mayo Clinic strongly believes in the PSA test and has the research to support that opinion, according to Dr. Blute. Their research shows that among men in their 50s and 60s living in Olmstead County, Minnesota, "incidence of late-stage prostate cancer has decreased since the mid-1990s when the PSA test caught on," says Dr. Blute. "We've also seen an overall decrease in the incidence of prostate cancer. And now, most importantly, we've seen a reduction in death rates."

James Talcott, MD, director of the Center for Outcomes Research at the Massachusetts General Hospital Cancer Center, is not so sure the decline in death rates is due to the PSA test. "It's possible," he says, "that the improved statistics may be due to other factors like changes in men's diets and how data are collected."

Despite disagreement among the medical community, conventional medical wisdom increasingly favors using the test, even for men who have no symptoms or family history. According to Jeff Engelsgjerd, MD, a urologist at St. Mary's/Duluth Clinic, the PSA test is, for now, the best way to detect early stage prostate cancer, when it is most treatable.

"It's not a perfect test," he says, "but for now, it's the best thing we have." Dr. Engelsgjerd recommends that all his patients over age 50, regardless of risk factors, have a yearly PSA test and digital rectal exam.

In February 2000, the American Urological Association (AUA) convened a panel of doctors who developed a set of PSA test recommendations and policies. The panel agreed that PSA tests are at least partially responsible for the dramatic increase in detecting prostate cancer and finding most prostate cancers before they spread outside the gland. The panel also recommended that PSA tests be used in conjunction with digital rectal exams.

"There is still controversy about whether the PSA test saves lives," says Dr. Blute. "However, the AUA panel of experts believes it will eventually be proven that it does save lives."