PSA Level Rising Can Be Cancer Indicator

By LAURAN NEERGAARD

WASHINGTON – How fast a man’s PSA level is rising – even before it’s high enough to trigger a doctor’s alarm – may signal that he has a life-threatening form of prostate cancer when the tumor is still small enough to be curable, researchers said Tuesday.

A new study backs a small but growing trend of evaluating the common blood tests in a more in-depth way, in hopes of better predicting who has aggressive cancer that needs aggressive treatment and who just needs monitoring.

The study is far from proof that making health decisions based on so-called PSA velocity can save lives.

But the findings suggest men should consider getting a first PSA test around age 40, instead of the more usual 50, to use as comparison for future changes, contends Dr. H. Ballentine Carter of Johns Hopkins University, the study’s lead author.

"The rate at which a man’s PSA rises may be more important than any absolute level for identifying men who will develop life-threatening cancer while their disease is still curable," he said.

"This is a test that doesn’t just diagnose prostate cancer. It diagnoses prostate cancer that’s going to actually cause harm."

PSA tests are a recommended way to screen for prostate cancer, but they’re imprecise. Too much PSA, or prostate-specific antigen, in a man’s blood can indicate that he has either a benign enlarged prostate or cancer. Only a biopsy can tell the difference.

It’s not even clear when is the best time to do a biopsy. Some men have cancer despite a "normal" PSA count of 4 or below. Yet routinely biopsying men with low PSA would worsen another problem, overdiagnosis. Many specialists say too many men today are undergoing side effect-prone treatment for tumors too small and slow-growing to ever threaten their lives.

The new study, published in the Journal of the National Cancer Institute, suggests that evaluating how fast a man’s PSA level rises may help that tricky balancing act of when to biopsy and how aggressive to treat.

Some 234,000 U.S. men will be diagnosed with prostate cancer this year, and just over 27,000 of them will die, the cancer society estimates.

Two years ago, Boston researchers reported that men whose PSA level jumped more than 2 points the year before diagnosis were more likely to relapse and die despite prostate surgery. But those were men whose PSA level was already fairly high.

Hopkins’ Carter wondered if doctors could catch such men far sooner, when the cancer might be more treatable.

He turned to a study of aging that has been collecting and freezing blood samples from participants since 1958. The Hopkins team tracked PSA changes in that blood from 980 men, 20 of whom eventually died of prostate cancer and 104 of whom survived it.

How fast a man’s PSA was rising a decade before his cancer was diagnosed – even before it reached that biopsy-triggering level of 4 – predicted his survival 25 years later, regardless of his ultimate cancer treatment, Carter concluded.

Those with a higher PSA velocity – the level rose more than a count of 0.35 a year – had a 54 percent survival rate, while those whose PSA rose more slowly had a 92 percent survival rate.

What does that mean for men today? That it’s a good idea to order a biopsy for a man with a low but fast-rising PSA, Carter said. And men diagnosed with prostate cancer whose PSA is rising slowly may be ideal candidates for monitoring instead of surgery or other treatment, he added.

A study with just 20 deaths is far too small to prove the value of PSA velocity, cautioned Dr. Durado Brooks, a prostate specialist with the American Cancer Society.

Still, growing numbers of doctors are using the method already to help decide when to order a biopsy, and "I think the study does raise the question as to whether PSA velocity may at some point be a helpful factor in determining prognosis," he said.

The work is "another step on the road to more sophisticated" prostate cancer screening and treatment, Dr. Timothy Church of the University of Minnesota wrote in an editorial accompanying the work.