A new Mayo Clinic (Rochester, Minnesota) study looked at the association between prostate-specific antigen (PSA) levels and prostate size and found that routine annual evaluation of prostate growth is not necessarily a predictor for the development of prostate cancer. However the study suggests that if a man's PSA level is rising quickly, a prostate biopsy is reasonable to determine if he has prostate cancer. The findings are being presented this week at the North Central Section of the American Urological Association in Scottsdale, Arizona.

Study investigators were trying to find out if a man with a rising PSA level would also have a proportional increase in prostate size.

"We found that men with or without prostate cancer have similar rates of prostate growth," Rodney Breau, MD, a Mayo Clinic urologic oncology fellow who led the study, told Medical Device Daily.

So if a man's PSA rises quickly, Breau believes he should have a prostate biopsy to determine if he has prostate cancer and this assessment of change in prostate size should not influence the decision to biopsy.

"This is the fist long-term, large study where prostate volume was assessed with ultrasound," he said. "It was a unique opportunity to find out which ones developed prostate cancer and to evaluate something we've never been able to look at before."

The findings were based on data in the Olmsted County Study of Urinary Health Status among Men, which includes a large cohort of men living in Olmsted County, Minnesota. Researchers randomly included 616 men between the ages of 40 and 79 who did not have prostate disease. All were examined every two years for 17 years with the PSA and prostate volume measurements using ultrasound, to determine changes in prostate disease.

From that group of men, 9.4% developed prostate cancer. Men who were diagnosed with prostate cancer had a faster rise in PSA levels (6%/year) compared to men who were not diagnosed with cancer (3.3%/year).

But the increase in prostate size was basically the same for the two groups.

"There's no question that there's an association between prostate size and PSA, but we're finding men with low PSAs are at risk and those with high PSAs aren't at risk," Breau said. "So we're looking at other variables."

So change in size doesn't explain the differences seen in men to develop cancer and those who don't. In fact Breau acknowledged that most men's prostates grow over time and their PSAs gradually become elevated as they age. What does that mean for diagnostic and screening practices now?

"A rising PSA over time, regardless of baseline, should be considered suspicious and they may need a biopsy," he said. "My philosophy is that if a man's PSA is changing at a high enough rate, I'm worried that something may be going on."

Breau also commented that the controversy of prostate cancer screening is not over diagnosis, but over treatment.

"Even if it's a small volume, low-grade cancer, they need an educated decision," he said. "I would rather know and be able to follow it in appropriate manner. The biggest problem is that a cancer diagnosis does not always need treatment. Many can be followed safely with active surveillance.

"We are at risk for being too complacent if we stop screening men," he said.

The Olmsted County Study is a long-term effort that will continue to provide more information. Most men started the study while in their 40s and now are in their 60s.

"A lot of men are entering the age group where there is higher risk of prostate cancer," Breau said. "A lot of exciting information will be coming to look at more specific trends in PSA and prostate volume that will allow us to be more selective on who does or doesn't need a biopsy."

Breau said he was a bit surprised by the study findings, originally expecting that men who did not have prostate cancer would have higher rates of prostate growth because PSA is driven by benign tissue.

"But they were identical," he said. "Those with cancer and those without had similar rates of prostate growth. I would have expected it to be different."

Lynn Yoffee, 770-361-4789;
lynn.yoffee@ahcmedia.com