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 recently from the journal Cancer showed that for those with the lowest baseline levels of prostate-specific antigen (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 tumours early while avoiding false positives that trigger unnecessary tests and treatment. This 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 between 50-55 years, 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, US, in a telephone interview. “We are starting to realize that there are men who don’t benefit from treatment, especially intensive screening."

Brawley says a man with a low PSA level in this age group may wait five-six years before having another PSA test if he chooses to have the test done at all.

Most common cancer

Routine screening: The American Cancer Society does not recommend it.

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 non-cancerous 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, who were part of the European Randomized Study of Screening for Prostate Cancer in the Netherlands, Sweden and Finland.

William Catalona, director of the clinical prostate cancer programme at Northwestern Memorial Hospital in Chicago, says 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% after 14 years in a study, though overall mortality barely changed as patients died of other causes.

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 says. “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. 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. ©2010/The New York Times

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