It seems logical that early detection for a disease that can kill is a good thing. But no one has yet demonstrated -- beyond a shadow of a doubt -- that the PSA test saves men's lives.
Prostate tumors are unlike most tumors, due to a wide variation in how they behave, says Dr. Philip Kantoff, an oncologist and director of the Prostate Cancer Clinic at Boston's Dana-Farber Cancer Institute. Some prostate tumors spread rapidly to bones and other organs. Others remain dormant for decades. Dr. Kantoff estimates that 8 million men in the United States have prostate cancer right now. Most will remain blissfully unaware of it throughout their entire lives.
"More men die with prostate cancer than from it," says Dr. Kantoff. Prostate cancer is present in 30 percent of men over age 50, and it becomes even more common with each passing decade. But many tumors are "clinically insignificant," he says. The difficulty lies in distinguishing these from potentially lethal ones. There's no way to predict, with total accuracy, which tumors will turn deadly.
In the past, prostate cancer was discovered when a doctor felt a suspicious lump or when it caused pain or trouble with urination. By then, the cancer had often already spread. Today, the disease is almost always found much earlier, and the PSA test is widely hailed as the reason.
But here's the reason for the controversy: The test generates a high number of false positives, often creating unnecessary anxiety. Even if cancer is found, it may not be the deadly kind. Conversely, a PSA reading can be normal even in the presence of cancer.
"The key is if PSA testing will decrease mortality rates," says Dr. Peter R. Carroll, a urologic oncologist at the University of California, San Francisco Medical Center. "I think it will, but the question will be, 'At what price?' "