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A PSA "Bounce" Probably Doesn't Mean Recurrence of Prostate Cancer

Oncology

     Naturally, this phenomenon, dubbed a PSA bounce, can cause anxiety. "When it goes up, it scares the devil out of men," said Frank A. Critz, M.D., medical director at the Radiotherapy Clinics of Georgia in Decatur and lead author of a study that appeared in the April issue of the Journal of Urology.

     But that PSA bounce is usually harmless.

     Brachytherapy, or the insertion of radioactive pellets directly into the prostate to deliver a continuous and uniform dosage of radiation to the gland, is one treatment option for men diagnosed with disease confined to the prostate.

     The most common way to gauge disease progress is by monitoring PSA levels in the blood. Rising PSA can be a sign of benign or malignant prostate conditions. Anecdotally, clinicians who specialize in brachytherapy have noted that a significant minority of men who undergo the procedure experience an increase in PSA levels many months after the procedure.

     "We were seeing this phenomenon where the PSA would fall, then go up, then go down," Critz added.

     For the study, Critz and his team tracked 779 men treated at his medical center. They found that PSA bounce occurs in 35 percent of men treated with brachytherapy.

     Among this group, the median time of PSA bounce -- defined as an increase in PSA level of 0.1 nanogram per milliliter (ng/ml) of blood or greater, followed by a subsequent decrease -- was 18 months after seed implantation.

     Among the men who experienced a bounce, 36 percent had one that lasted 12 months or more, and 22 percent of the men had more than one bounce. The median PSA increase was 0.4 ng/ml, with a range of 0.1 to 15.8 ng/ml.

     "It's something that physicians and men should be aware of," Critz said.

     The tricky part is distinguishing between a harmless PSA bounce and a PSA elevation that indicates cancer progression. Critz explained that while brachytherapy works immediately to halt cancer growth, it takes a couple of years for the radiation to kill the cancer cells and cause them to disintegrate.

     "You can't biopsy for bounce, because the cancer cells, with radiation, take time to disintegrate," Critz said.

     If a physician were to conduct a biopsy, he or she might collect some of these moribund cancer cells. This in turn might prompt that clinician to conclude that the cancer was still active and growing and prescribe unnecessary hormone therapy.

     In his study, Critz found that men who had an actual recurrence experienced one in a median time of 30 months, significantly beyond the median 18-months-past-implantation point at which a bounce typically occurs. And only 17 percent of men with recurrence had a bounce before recurrence. Also, 92 percent of men who had a bounce had it within three years. This suggests that when the bounce occurs may be the key to distinguishing between a bounce and recurrence.

     "Past three years, it's very uncommon to have a bounce, and any rise after this point is most likely recurrence," Critz said.

     He explained that the bounce is thought to be due to inflammation of the prostate, a condition that causes PSA levels to rise independently of any possible cancer. Men who undergo brachytherapy and have a bounce also experience symptoms of an inflamed prostate, such as a burning sensation during urination.

     "We think [PSA bounce happens] because of delayed inflammation of the prostate as a result of the radiation treatment," said Critz, who will continue to study how brachytherapy affects PSA levels.

     PSA bounce has been well known among physicians who perform the procedure, said David C. Beyer M.D., of Arizona Oncology Services in Scottsdale, but this is the first large-scale attempt to quantify the phenomenon.

     "This confirms the conventional wisdom that roughly one third of men will have a completely benign bounce after brachytherapy," he said.

     The message for men who have brachytherapy, Beyer added, is they should be aware that an elevation of the PSA is common and requires no diagnostic workup or therapy unless it is sustained over more than six months.

     "This adds further support to the general concept that the trend of multiple PSA readings over time is more important than [looking at] a [single] arbitrary PSA level," he said. "In evaluating the PSA after implants, it can now be truly stated that patience is a virtue."

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