Description: TUESDAY, May 29 (HealthDay News) -- A rapid rise in blood levels of prostate specific antigen (PSA) over the course of a year -- a diagnostic indicator known as "PSA velocity"-- is the single most important marker for a particularly aggressive and deadly form of prostate cancer, new research suggests.

Reporting in the July 1 issue of Cancer, the authors say that an increase by two points or more of PSA over one year is a better predictor of death from prostate cancer than either a one-time "snapshot" of PSA levels at diagnosis, or a doctor's assessment of the stage of cancer prior to treatment.

"We know that, without any other factors, PSA velocity is a very good predictor of prognosis," said study leady author Dr. Anthony V. D'Amico, the chair of genitourinary radiation oncology at Brigham and Women's Hospital and professor of radiation oncology at Harvard Medical School in Boston. "It all depends on where it's been and where it's going," he said.

The American Cancer Society