Many older men with low readings in a blood test for prostate cancer now given annually may be able to safely have the screenings less often, a change that could save hundreds of millions of dollars annually.
A large new study concludes that many can safely have the test every two years or even five years, since those with low PSA scores face little chance of a sudden change for the worse.
About half of all men over age 50 now get regular PSA tests, which scan the blood for a protein that goes up as prostate cancer develops. The higher the score, between 1 and 4, the more likely a man will go on to develop prostate cancer.
No one knows how often a man should be tested. Prostate cancer is the second most common cancer in men, and will affect 189,000 American men in 2002 and kill 30,200, according to the American Cancer Society.
Dr. E. David Crawford of the University of Colorado, who directed the analysis, presented the results Monday at a meeting in Orlando of the American Society of Clinical Oncology.
"When we first thought about screening, we thought it should be done every year," he said. "We had no data to suggest otherwise. Now we have data that lets us step back.
"We found that the vast majority of men whose initial PSA levels are very low do not need to worry that they would skyrocket within one year," Crawford told a news conference.
The new study concludes:
- If a man's initial PSA reading is between zero and one, he can wait five years before having another test.
- If the reading is between one and two, he can wait two years before another test.
- Those whose readings are between two and four should continue to have annual tests.
Researchers said that if their new guidelines are followed, the less frequent testing would cut the number of PSA tests each year in half, saving between $500 million and $1 billion.
The study was designed primarily to ask a bigger question: Does early detection of prostate cancer save lives? The answer is not in yet. So far, there are no results from any research to prove that finding the cancer sooner does any good, although many doctors believe early detection saves lives.
"This is a slow-growing, indolent disease," Dr. Charles Balch, executive vice president of ASCO, said in an interview.
"It gives us a large window of time."
ASCO President Dr. Larry Norton said the findings would have an immediate effect. "Right away this will change recommendations in terms of PSA testing," he told reporters.
"These findings sit amid a much larger controversy about whether PSA screening should be done at all," said Dr. Steven Woolf of Virginia Commonwealth University.
Falsely positive test results cause anxiety and lead to unnecessary biopsies. Furthermore, many men live with slow-growing prostate cancers that never cause any problems. Finding and removing them can cause incontinence and impotence without giving any benefit.
"It's important to understand there are potential benefits to screening, but people also need to understand more about the harms of screening," Woolf said.
The latest study found that when men's PSA readings are between zero and 1, 98.7 percent will still have a reading under four when tested again five years later. For those with readings between one and two, 98.8 percent will still be under four when tested two years later.
Whether a cutoff of four will remain as the point of concern is not clear. Some doctors already suggest that more testing should be done if men's PSA levels go above 2.6.
The American Cancer Society now recommends that annual PSA testing and a digital rectal exam be offered to men beginning at age 50 if they have a life expectancy of at least 10 years.
Dr. Harmon Eyre, the cancer society's research director, said the latest study findings look reasonable.
"I won't say that we will immediately change our guidelines, but we will take a careful look at it," he said.
Besides the absolute PSA number, doctors also take into consideration how fast the level is rising, the size of the man's prostate and his age when deciding how aggressively to react to their readings.
For instance, men with enlarged prostates often have higher PSA readings, although this does not necessarily mean they have cancer.
When readings are between 4 and 10, experts say there is about a 40 percent chance the man has prostate cancer. Over 20, the risk is virtually 100 percent.
The National Cancer Institute is running a large study aimed at showing whether screening for a range of cancers, including breast, prostate and ovarian cancer, pays off in terms of lives saved.