Prostate Cancer Screeing at Age 40?
Beginning Prostate-Cancer Screening
At Age 40 Holds Benefits, New Data Show
November 7, 2006
Most men don''t start prostate-cancer screening until the age of 50. But now there''s new evidence that starting at 40 could not only catch the worst cancers but could also spare men from unnecessary treatments later in life.
The idea of screening men at a younger age for prostate cancer is controversial. Widespread prostate-cancer screening has been blamed for unnecessary biopsies and overtreatment for prostate cancer.
While screening even younger men would seem to compound the problem, some new research suggests the opposite may be true. Scientists at Johns Hopkins University School of Medicine in Baltimore have shown that screening men at 40 can help doctors better interpret screening scores as men age, resulting, they say, in fewer unnecessary procedures.
The screening test for prostate cancer is called the Prostate Specific Antigen, or PSA, test. It''s a blood test that measures a protein produced by the prostate gland. As a result of PSA testing, about 1.6 million biopsies are conducted each year, but only 234,000 men are diagnosed with prostate cancer. The challenge for doctors has been how to interpret the results of a PSA test. Doctors generally view a PSA from 0 to 2.5 ng/ml as low, while 2.6 to 10 ng/ml is considered slightly to moderately elevated.
The new Johns Hopkins study shows that a single PSA score isn''t all that useful, and that what really matters is the rate at which PSA scores change over time. Trouble is, most men start getting PSA tests at 50, and there''s no historical PSA information to help doctors decide if a test score is worrisome or just normal for that particular man.
"We have been focusing on PSA as a marker of prostate cancer assuming that everyone who has a PSA that is elevated or going up is at risk for cancer, and that triggers a biopsy," says H. Ballentine Carter, professor of urology/oncology at Johns Hopkins. "But instead of using a single threshold, we should focus more on how fast the PSA got to a given point."
One problem with starting PSA screening at 50 is that many benign prostate conditions, such as inflammation or enlargement of the prostate, can cause spikes in PSA levels, making the test less reliable. However, if screening is started at a younger age, doctors will have more information about a man''s prostate health over the years, helping them to distinguish between benign conditions, nonaggressive cancer and lethal cancers.
• Eating a diet high in red meat and high-fat dairy products.
• Lack of exercise.
• Being over 65 years old.
• Vasectomy before the age of 35.
• Annual increase in PSA score of 0.35 ng/ml or higher.
The John Hopkins study, published this month in the Journal of the National Cancer Institute, looked at PSA scores from 980 men in the Baltimore Longitudinal Study of Aging, the country''s longest-running scientific study of human aging. The researchers looked at the pattern of PSA scores, comparing scores from healthy men with those who died of prostate cancer. What was so notable about the review of the BLSA data is that it could predict 10 to 15 years before diagnosis which men were going to have life-threatening cancers, even when their PSA scores were still relatively low.
There are several ways the BLSA data can help men not only avoid unnecessary treatment but also to make better decisions about their care if they are diagnosed with prostate cancer.
According to Dr. Carter, a 40-year-old man with a PSA score of 0.6 or lower needs less frequent monitoring and likely only needs repeat tests at the age of 45 and 50.
However, if a 40-year-old has a score above 0.6, he should be checked every two or three years. Most of these men won''t have cancer, but regular testing will develop a PSA history that will make it easier for doctors to interpret their PSA scores when the men are in their 50s and 60s.
The data show that a man whose PSA score rises by 0.35 ng/ml or more each year will see a fivefold increase in the risk of dying from prostate cancer in the next two to three decades. By finding those men in their 40s, doctors can intervene when the cancer is more easily treated and the man is less likely to have complications.
And using "PSA velocity" can help identify men who have slow-growing cancers that don''t need any treatment.
For instance, a 40-year-old man who has a PSA of 0.8 at 40 and then a score of 2 a few years later likely is at high risk for aggressive cancer. But if he has a score of 2 and no prior PSA test, he likely would be told he''s at low risk. By the time his PSA score reaches 4 and doctors decide to intervene, it might be too late to save him.
Meanwhile a 50-year-old man with a PSA of 4 likely will be told he needs a biopsy. However, if that man at the age of 40 had a PSA of 2, the 10-year trend suggests he likely doesn''t have cancer or at least not an aggressive cancer.
"It''s the same threshold of 4," says Dr. Carter. "But the two people got to that threshold at much different rates. I see this as a way to decrease the men who have biopsies and identify the men with lethal disease."