Atlanta-Young men with PSA velocities greater than 0.5 ng/mL/year are at significantly greater risk for prostate cancer, researchers report in a new study. This suggests that the traditional recommendation of a threshold of 0.75 ng/mL/year to distinguish prostate cancer from benign conditions would miss a substantial proportion of prostate cancers among men younger than 60 years of age.
While physicians traditionally have recommended biopsies at PSA cutoff points of 4.0 ng/mL, this cutoff also might be too liberal for younger men, according to study author Robert B. Nadler, MD, associate professor of urology, Feinberg School of Medicine, Northwestern University, Chicago. He presented his research at the AUA annual meeting here.
Dr. Nadler and his colleagues studied a group of men between 1989 to 2001 who were participating in a large prostate cancer screening study. Of the approximately 36,000 men in the study, 6,844 were younger than 60 years at entry, and 346 of those younger men were subsequently diagnosed with prostate cancer. Researchers calculated PSA velocity in those 346 men, using regression analysis the year prior to diagnosis. They examined PSA velocity thresholds for prediction of prostate cancer risk and used multivariate analysis to determine whether PSA velocity was an independent predictor of prostate cancer in men younger than age 60.
"We found that 0.4 ng/mL/year was the best value to help discriminate which young men have prostate cancer, while at the same time, doing the fewest amount of unnecessary biopsies," Dr. Nadler said.
In the study, multivariate analysis restricted to the subgroup of men with total PSA levels of less than 2.5 ng/mL had similar results.
"What we are saying is [that] PSA velocity is an important measurement. So if your PSA goes from 1.1 to 1.6 ng/ mL/year, that would be indicative of someone who needs a prostate biopsy, but would fall under the traditional total PSA threshold of 2.5 ng/mL," Dr. Nadler said. "Now we know that if your PSA is above the median for your age, you are at a higher risk for developing prostate cancer, so we are watching these patients more carefully than in the past."
The recommended PSA velocity to trigger a biopsy in younger men is 0.4ng/mL/year or higher, according to Dr. Nadler. These findings will change practice dramatically, especially among those physicians who still debate PSA screening and cutoff points or those who believe that the normal cutoff point is 4.0 ng/mL.
"PSA is probably best at predicting cancer in younger men, rather than older men," Dr. Nadler said. "The reason is that there is going to be less background noise from BPH, which also makes the PSA go up.