PSA Velocity and Doubling Time Better Predictors for Outcomes After
Radical Prostatectomy

November 10, 2005 — In the largest study of its kind to date, Mayo
Clinic researchers report that prostate specific antigen (PSA) kinetics,
both velocity and doubling time, can be used to predict disease
progression and likelihood of death after radical prostatectomy surgery,
suggesting that this could be used to guide treatment decisions. Study
results are published in the December issue of The Journal of Urology.

"The level of PSA in the blood has less prognostic value than we
previously thought, and we don't have another serum marker to help us,"
says Michael Blute, M.D., Mayo Clinic urologist and lead investigator of
the study. "It was important for us to find other ways to look at PSA
data and translate that into information that will save lives, and I
believe we have done that."

Dr. Blute and his fellow researchers reviewed the records of 2,290
patients with multiple preoperative PSA measurements, as well as 5,176
patients with only one preoperative measurement, looking at the rate at
which PSA increased in the body — thought to indicate cancer growth.
This was measured as both the PSA velocity (PSAV), the rate of increase
in PSA levels over time, and the PSA doubling time (PSADT), a measure of
how quickly PSA levels double. The researchers found that while PSAV is
simpler to calculate, PSADT may be a better indicator of untreated
prostate cancer.

Over an average follow-up period of about seven years, cancer spread or
recurrence, and deaths from cancer were recorded. Biochemical
progression was noted in 25.5 percent of the patients, clinical
progression in 6.8 percent and cancer death in 1.8 percent. PSAV and
PSADT both predicted progression and death. PSAV greater than 3.4 ng/ml
yearly correlated to men being 6.54 times more likely to die than those
with lower PSAV. PSADT quicker than 18 months correlated to the risk of
death being 6.22 times higher than for those with longer PSADT.

"This provides valuable pretreatment prognostic factors for prostate
cancer," says primary author Shomik Sengupta, M.D. "We hope that our
work will help in the doctor-patient discussion and result in more
informed decisions relating to observation, intervention and adjuvant
treatment."

The study group consisted of patients who had undergone radical
prostatectomy for prostate cancer between 1990 and 1999 at Mayo Clinic.
Preoperative and postoperative PSA measurements were obtained from
referring physicians and/or Mayo laboratory testing.

Other Mayo Clinic researchers who contributed to this study include
Robert Myers, M.D.; Jeffrey Slezak; Eric Bergstralh; and Horst Zincke,
M.D., Ph.D.

knowledge is power - growing old is mandatory - growing wise is optional    
"Many more men die with prostate cancer than of it. Growing old is
invariably fatal. Prostate cancer is only sometimes so."
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