The PSA blood test widely used to detect prostate cancer can also predict who is most likely to die from the disease, researchers said on Wednesday.

The study, in this week’s New England Journal of Medicine, added to evidence that the rate of increase in prostate-specific antigen level may be more important for predicting cancer than the actual PSA number.

The researchers said their study of 1,095 men showed that men need annual PSA tests so that their year-to-year change - called PSA velocity - can be monitored.

They found that when PSA levels rose by at least 2 points during the year before surgery, about one in four patients died from prostate cancer within seven years. It raised the risk of death 10-fold.

But if the PSA level had been increasing slowly before surgery, there was very little chance the patient would die from a prostate tumor.

“This study provides, for the first time, solid evidence that PSA testing over a period of time is a reliable indicator of possible risk of death from prostate cancer,” said Dr. Anthony D’Amico of Massachusetts General Hospital in Boston, who helped lead the study.

Prostate specific antigen is a protein produced by cells in the prostate, the walnut-sized organ that sits against a man’s rectum and produces the semen that carries sperm. The higher the PSA, the more likely the prostate is irritated by an infection or, perhaps, by cancer.

Prostate cancer affects 220,000 U.S. men a year and kills about 29,000, according to the American Cancer Society.

PSA HIGH

If a man’s PSA looks high or looks like it has risen recently, a urologist will usually recommend a biopsy to remove some tissue from the organ to see if it is cancerous.

“A man whose PSA is 3.5 may have nothing to worry about if it was 3.49 the year before, but a lot to worry about if PSA last year was 1,” D’Amico said in a telephone interview.

Starting around age 35 or 40, men need annual screening to set their “baseline” PSA level, against which change can be measured, he said.

“The nice thing about starting at age 40 is most men at 40 have a PSA that is like 0.6 or something like that,” added Dr. William Catalona of Northwestern University in Chicago, who also helped direct the study.

“If your next annual PSA goes to 1.4, well, you shouldn’t wait until next year to check it again.”

This contradicts the usual guidelines, which suggest that men can relax until their PSA level reaches 4, Catalona said.

He got the idea of checking “PSA velocity” while doing a large study of 36,000 men over 12 years.

“I had some men come in and their PSA would be 0.6 one year, then 1.4 the next, then 2.4, then 3.2. There would be an obvious trend, and I would say ‘We can’t do a biopsy until the PSA reaches 4’,” Catalona added.

“Then they’d come in and have a PSA of 6,” he said. The men would get immediate surgery to get their prostates out and many times the cancer had already spread.

“Then they’d be really angry,” Catalona said.

Prostate cancer can be a slow-growing disease and some men are advised just to watch it carefully - especially if they are older and likely to die of something else before the prostate cancer becomes serious. (Additional reporting by Maggie Fox in Washington)