About two-thirds of positive results are not caused by cancer but by benign growth of the prostate. In addition, prostate cancer is a slow-growing cancer in most cases and might not merit treatment over the course of a typical man's life. Twice as many prostate cancers are caught in early stages now as were caught 15 years ago. Early detection may lead to better treatment . The test may catch very aggressive cancers early.
Treatment can have significant side effects, including impotence and incontinence.
Experts fear both treating patients who don't need surgery, which can cause life-ruining side effects, and undertreating men with aggressive cancer. A better test may be on the way, says Michael Brawer, director of the Northwest Prostate Institute in Seattle. In the body, PSA exists both combined with other compounds and in a free state. Excess of the combined forms spells trouble, Brawer says. Human kallikrein 2, a compound that makes PSA active, shows up in more aggressive cancers.