Screening for early detection of cancer sounds like a no-brainer, but it’s not an easy choice for men considering regular P.S.A. tests, which measure blood levels of prostate-specific antigen and are used to detect prostate cancer. Though use of the test is widespread, studies show that the screening saves few, if any, lives.
While the test helps find cellular changes in the prostate that meet the technical definition of cancer, they often are so slow-growing that if left alone they will never cause harm. But once cancer is detected, many men, frightened by the diagnosis, opt for aggressive surgical and radiation treatments that do far more damage than their cancers would have, leaving many impotent and incontinent.
As a result, major health groups don’t advise men one way or the other on regular P.S.A. screenings, saying it should be a choice discussed between a man and his doctor.
So how does a man decide whether to get P.S.A. screening or not? Finally, some new research offers simple, practical advice — at least for men 60 and older.
Researchers at Memorial Sloan-Kettering Cancer Center in New York and Lund University in Sweden have found that a man’s P.S.A. score at the age of 60 can strongly predict his lifetime risk of dying of prostate cancer, according to a new report in the British medical journal BMJ.
The findings also suggest that at least half of men who are now screened after age 60 don’t need to be, the study authors said.
The researchers followed 1,167 Swedish men from the time they were 60 years old until they died or reached 85. During that time, there were 43 cases of advanced prostate cancer and 35 deaths in the group. The researchers found that having had a P.S.A. score of 2.0 or higher at the age of 60 was highly predictive of developing advanced prostate cancer, or dying of the disease, within the next 25 years.
About one in four men will have a P.S.A. score of 2.0 or higher at the age of 60, and most of them will not develop prostate cancer, said the study’s lead author, Andrew Vickers, associate attending research methodologist at Memorial Sloan-Kettering. But the score does put them in a higher-risk group of men who have more to gain from regular screening, he concluded.
The higher the score at age 60, the greater the long-term risk of dying from prostate cancer, Dr. Vickers and his colleagues found. Men with a score of 2.0 or higher at age 60 were 26 times more likely to eventually die of the disease than 60-year-old men with scores below 1.0.
Still, the absolute risks for men with elevated scores were lower than might be expected. A 60-year-old man with a P.S.A. score just over 2.0 had an individual risk of dying from prostate cancer during the next 25 years of about 6 percent, the researchers found. A 60-year-old man with a P.S.A. score of 5 had about a 17 percent risk.
“Most of those men are going to be absolutely fine,” said Dr. Vickers. “But they can be told they are at high risk and they need screening.”
Men with a P.S.A. score of 1.0 or lower at age 60 had a very low individual risk of death from prostate cancer over the next 25 years, the study found: just 0.2 percent.
“They can be reassured that even if they have prostate cancer or get it, it’s unlikely to become life-threatening,” said Dr. Vickers. “There’s a strong case that they should be exempted from screening.”
The advice is less clear for men with scores between 1.0 and 2.0 at the age of 60. They still have a very low individual risk of dying from prostate cancer, judging from the new data. The long-term risk of dying from prostate cancer ranged from about 1 percent to 3 percent for these men, and the decision to screen may depend on their personal views and family histories, Dr. Vickers said.
While the findings don’t answer all of the questions associated with P.S.A. screening, they should give peace of mind to sizable numbers of men who decide not to continue regular testing. The results also will reassure men who decide to continue with regular screenings that the benefits most likely outweigh the risks.
Dr. Eric A. Klein, chairman of the Glickman Urological and Kidney Institute at the Cleveland Clinic, said that he would like to see the findings of the new study independently confirmed, but that other studies also have suggested that the risk of cancer is low in men whose P.S.A. levels remain below 1.5 in their 50s and 60s.
“We are in the midst of a paradigm shift in screening and risk assessment that no longer relies on a simple P.S.A. cutoff to determine who should be biopsied,” Dr. Klein said.
P.S.A. screening is already not advised for those 75 and older, because the slow-moving nature of the disease means that a vast majority of men at that age are likely to die from something other than a newly detected prostate cancer. A major study last year confirmed that P.S.A. testing is not helpful for men with 10 years or less of life expectancy.
But the advice continues to be murky for younger men. In a large European study reported last year, 50- to 54-year-olds didn’t benefit from screening. But men ages 55 to 69 who had annual P.S.A. testing were slightly less likely to die from prostate cancer than those who weren’t screened.
The researchers who conducted the latest study also have investigated whether a man’s P.S.A. score at 50 can predict his long-term risk. In a 2008 report of 21,000 men published in the journal BMC Medicine, the researchers found that two-thirds of the advanced cancer cases that developed over 25 years were in men who had a P.S.A. score of 0.9 or higher at the age of 50.
Those findings can help younger men decide how intensely they want to screen for the disease. A man whose P.S.A. test shows him to be at low risk at age 50 may decide not to be retested again until the age of 60. A man with a higher score may want to do more frequent testing.
“We haven’t solved every single problem with screening,” Dr. Vickers noted. “We need to screen fewer people, screen the right people, and we don’t have to treat every cancer we catch.”
NYTimes
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