'PSA Bounce' After Prostate Cancer Treatment Doesn't Affect Survival

WEDNESDAY, Nov. 8, 2006 (HealthDay News) -- For men with prostate cancer, a rise in PSA levels after radiation therapy -- called PSA bounce -- is not clinically relevant and doesn't affect survival, researchers from Fox Chase Cancer Center report.

In addition, another study by other Fox Chase researchers shows that a rapidly rising PSA level before treatment is a sign that the cancer has most likely spread beyond the prostate and that hormone therapy, in addition to radiation, is called for.

The findings of both studies were to be presented Wednesday at the 48th annual meeting of the American Society for Therapeutic Radiology and Oncology, in Philadelphia.

In the first study, researchers led by Dr. Eric Horwitz, clinical director of Fox Chase's Radiation Oncology Department, sought to determine whether there was a difference in survival between men who had a PSA bounce after radiation therapy, compared with men who didn't.

The researchers collected data on more than 7,500 men treated either with external-beam radiation or with radioactive seed implants. They found that a significant number of men had at least one PSA bounce within one to three years after treatment. However, there were no differences in survival of patients who had a bounce and those who didn't.

"PSA bounce, which happens in 50 percent of men who get treated with radiation, doesn't have any clinical significance," Horwitz said. "It does not mean that your cancer comes back."

Horwitz noted that, in the past, a PSA bounce was thought to mean that the cancer had returned and the patient needed hormone treatment. "Hormone treatment has many side effects," he said. "If the cancer has not returned, you certainty don't want to have additional treatment."

Prostate-specific antigen (PSA) is a protein produced by the prostate gland. A PSA test measures levels of PSA in the blood. It's normal for men to have low blood levels of PSA, but prostate cancer can increase PSA levels.

Dr. Durado Brooks, director of prostate and colorectal cancers at the American Cancer Society, thinks this study should help reassure men that PSA bounce doesn't mean their cancer has returned.

"It appears that PSA bounce after radiation is insignificant," Brooks said. "This transient increase doesn't seem to make any difference in long-term survival. This should be reassuring to men."

In the second study, Dr. Mark K. Buyyounouski, an attending physician in Fox Chase's radiation oncology department, and colleagues collected data on 671 men with clinically localized prostate cancer who received 3-D conformal radiation therapy between 1989 and 1999.

They found that the rate of rise in PSA levels, known as PSA velocity (PSAV), can determine when prostate cancer may have already spread, even in men with clinically localized disease.

"Men whose PSA is rising rapidly prior to treatment appear to be at higher risk for having disease outside of the prostate," Buyyounouski said. "This has been shown to be a risk factor for death from prostate cancer."

Buyyounouski's team found that when PSAV was greater than 2 nanograms per milliliter per year, PSA was likely to continue rising at the same rate despite radiation therapy. In addition, men with a rapidly rising PSAV were more likely to have a cancer spread beyond the prostate and a greater risk of dying from the disease. But, this relationship was not seen for men with a PSAV of less than 2 nanograms per milliliter per year.

"These men with a rapidly rising PSA need treatment to more than the prostate area," Buyyounouski said. "They should strongly consider hormone therapy, which is the standard of care for men with a high risk of distant spread of cancer."

Hormone therapy has been shown to improve survival for men at high risk of undetected spread of prostate cancer, Buyyounouski noted.

Brooks said: "This study is in line with a lot of other work that has been done in PSAV. There is a growing body of evidence that supports the fact that a rapid rise in PSA is associated with more severe disease and possibly with worse long-term outcome."

More information

The U.S. National Cancer Institute can tell you more about prostate cancer.