Men ages 55 and older who have low scores on their first standard screening to detect prostate cancer benefit the least from repeating the test, a study found.
Research released today from the journal Cancer showed that for those with the lowest baseline levels of prostate-specific antigen, or PSA, 24,642 men would have to be screened and 724 cases of prostate cancer would have to be treated to prevent one death. That compares with 133 screened and 60 treated to prevent one cancer death in men with the highest baseline PSA levels.
The study adds fresh evidence to a debate about how to screen for prostate cancer to catch tumors early while avoiding false positives that trigger unnecessary tests and treatment. Today’s study tried to identify which men would benefit most from additional screening based on their first PSA test.
“This paper suggests that a man with a low PSA at the age of 50 to 55, even if he were to develop cancer, is not likely to have one of the cancers that’s likely to be harmful,” said Otis Brawley, chief medical officer of the American Cancer Society in Atlanta, in a Sept. 10 telephone interview. “We are starting to realize that there are men who don’t benefit from treatment, especially intensive screening.”
Brawley said a man with a low PSA level at ages 50 to 55 may wait five to six years before having another PSA test if he chooses to have the test done at all.
Most Common Cancer
Prostate cancer is the most common malignancy other than skin cancer to occur in U.S. men, and is the second-leading cause of cancer death, behind lung tumors, according to the cancer society. This year, 217,730 men in the U.S. will be diagnosed with prostate cancer and more than 32,000 will die, according to the National Cancer Institute.
Prostate cancer is slow growing and many men live with the disease without knowing of its existence.
Prostate-specific antigen is a protein made by the prostate gland. The PSA test itself can’t detect cancer. Higher PSA scores may be caused by cancer cells or by a noncancerous enlarged prostate or by infections and inflammation.
The researchers in the study compared the number of people who developed prostate cancer with those who died from the disease as it related to PSA levels. They included 43,987 men ages 55 to 74 years who were part of the European Randomized Study of Screening for Prostate Cancer in the Netherlands, Sweden and Finland.
Northern Ireland Comparison
They also looked at another 42,503 men from Northern Ireland who had a baseline test without systematic repeat screenings. The participants were followed for about nine years.
They found that 5,861 men developed prostate cancer and 345 died. Men with the highest PSA levels at the start of the study were the most likely to die from the disease, the research showed.
“This is the first study that provides additional information on how the harms and benefits of screening, early detection and treatment might be distributed in relation to PSA levels,” said lead study author Pim van Leeuwen, a doctor in the Department of Urology at Erasmus University Medical Center in Rotterdam, the Netherlands, in a Sept. 10 e-mail.
“We conclude that serum PSA before diagnosis is a strong predictor for prostate cancer mortality,” van Leeuwen said. “Baseline PSA might be used for a risk assessment that balances the harms and benefits of early detection in men aged 55 to 74 years.”
Anthony D’Amico, chief of Genitourinary Radiation Oncology at Brigham and Women’s Hospital in Boston, said the average of nine years of follow-up in the study wasn’t long enough to show a benefit in those whose first PSA tests were low.
“This is an attempt to individualize PSA screening. It’s limited by the lack of long-term follow up,” D’Amico, who wasn’t involved in the study, said Sept. 10 in a telephone interview. “I don’t think this study is going to change anything.”
William Catalona, director of the clinical prostate cancer program at Northwestern Memorial Hospital in Chicago, said the men in the study need to be followed for at least 15 years. Catalona ran the research that pioneered the use of PSA tests as a screening tool to check for prostate cancer.
A study earlier this year from the University of Gothenburg in Sweden showed that PSA tests helped reduce deaths from the disease by almost 50 percent after 14 years in a study, though overall mortality barely changed as patients died of other causes. In that study, the researchers said 293 men need to be screened and 12 diagnosed with prostate cancer to save one from dying of the disease. Most of the benefits of prostate-cancer screening occur after 10 years, the researchers said.
Cancer Society Recommendations
The American Cancer Society doesn’t recommend routine screening at any age for prostate cancer and leaves the decision to the patient and his doctor. Those who choose to be screened with a PSA may take the test every other year if they have low levels rather than every year as suggested previously.
“There is increasing acceptance in the urologic community that a substantial number of men who have prostate cancer have a kind of prostate cancer that doesn’t need to be treated, it needs to be watched,” Brawley said. “We need a better test than PSA for the detection of prostate cancer. Once we detect prostate cancer, we need a genomic test that tells us the cancers that need to be watched versus the cancers that are going to kill.”
Men who have elevated PSA tests are often urged to have a biopsy, a procedure that removes tissue from the prostate to look for the presence of cancer cells. The biopsies can be inconclusive in showing whether a patient has cancer cells that are growing fast enough to pose a threat. Those patients are often urged to get treatment for cancer, according to Thomas Neville, author of a recent study on prostate cancer testing.
Surgery, radiation, hormone therapy and chemotherapy are common procedures for prostate cancer. Treatment may be painful and sometimes leads to lifelong urinary incontinence and impotence, according to the National Cancer Institute.