Prostate Cancer in 15% of Men With Normal PSA
Best Test May Be to Follow PSA Levels Over Time, Expert Says
Should Doctors Look for Trouble?
How hard should doctors look for prostate cancers? In an editorial accompanying the Coltman team's study, Johns Hopkins researcher H. Ballentine Carter, MD, notes that a man's lifetime risk of prostate cancer is 16%. Yet his risk of dying from prostate cancer is only 3%.
"In the age range of 60 years to 80 years, about 30% to 40% of men have small prostate cancers," Carter tells WebMD. "Now, this article tells us, we have the ability today to detect those."
If doctors look harder for prostate cancers, they will find them. If they do this, a lot of men will have unnecessary surgery or radiation therapy. If they don't, some men who might have been saved by early detection will die.
"We already know we are overdetecting the disease," Carter says. "A lot of men who have prostate cancer are not going to have their disease harm or bother them during their lifetimes. Unless they were biopsied, they never would have known that they had prostate cancer during their life. The lower we set the PSA threshold, the more unnecessary treatments we'll have."
Like Coltman, Carter says a man's risk factors for prostate cancer have to be taken into account. But he would be very careful about sending a man with a midrange PSA level to get a biopsy.
"If I met someone in their 60s at a PSA level of 2.5 or 3.0 or 3.5, I would say, 'Look, there is a high probability you do not have prostate cancer. Let's monitor your PSA over time and see if it changes,'" Carter explains. "There shouldn't be any urgency to try to detect these tumors when PSA is in this range. These tumors grow very slowly. They still will be curable later when their PSA is 4."
Carter warns that it's a different story for men in their 40s. For them, a midrange PSA level may well mean trouble.
"These are the men we should be concerned about if they have a prostate level of 2.5 or 3," he says.
Carter suggests that more important than a single PSA test is the speed at which PSA levels change over time. An increase of 0.5 ng/mL to 0.75 ng/mL during the course of a year is worrisome, he says. Coltman, however, says he wonders whether most men would be comfortable waiting for a year to find out whether they have cancer.
Coltman and Carter agree that better tests for prostate cancer are sorely needed. These yet-to-be-invented tests would find some marker on prostate cancer cells. It is hoped the marker would show not just that the cancer is there, but whether it is a cancer a man has to worry about.