WEDNESDAY, Nov. 4 (HealthDay News) -- Prostate cancer patients whose prostate-specific antigen (PSA) levels rise within 18 months after radiotherapy have an increased risk of death, say U.S. researchers.

Their study included more than 2,100 patients with clinically localized prostate cancer who experienced biochemical failure (lowest PSA level plus 2 nanograms per milliliter) after treatment. The median interval between treatment and biochemical failure was 35.2 months, but 19 percent of patients developed biochemical failure at 18 months or less.

Five-year, cancer-specific survival for patients who developed biochemical failure within 18 months was 69.5 percent, compared with 89.8 percent for those who developed biochemical failure more than 18 months after treatment.

The study was to be presented Wednesday at the annual meeting of the American Society for Radiation Oncology in Chicago.

"PSA is the gold standard for following prostate cancer patients after they receive radiation or surgery. But we haven't known if having PSA rise sooner means a patient has a greater danger of dying of prostate cancer, though it seems logical," study leader Dr. Mark K. Buyyounouski, a radiation oncologist at the Fox Chase Cancer Center in Philadelphia, said in a news release from the center.

"Now we can use the simple criteria from this study, which is widely available for anyone who has PSA testing, to identify men who have a greater than 25 percent chance of dying from prostate cancer in the next five years. That is huge. There is nothing else that can do that."

Currently, biochemical failure alone doesn't prompt treatment. Doctors usually wait until a patient's PSA reaches a high level or there is some other evidence of tumor spread.

This study suggests that treatment can begin "far sooner without waiting for other signs or symptoms of prostate cancer," Buyyounouski said. "If a patient has biochemical failure at 16 months, rather than wait and learn later that the PSA is rising sharply and risk the development of distant metastasis, therapy can be started sooner based on the increased risk of death."

More information

The American Cancer Society has more about prostate cancer.

-- Robert Preidt

SOURCE: Fox Chase Cancer Center, news release, Nov. 4, 2009

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