WEDNESDAY, Sept. 15 (HealthDay News) -- Fresh on the heels of a similar report released earlier this week, a new study shows that men who have a low prostate-specific antigen (PSA) level at 60 do not really need future screening.
Conversely, men with a high PSA reading -- 2 nanograms per milliliter (ng/ml) or above -- should be monitored and have an increased risk of developing the disease, the researchers added.
"If you have a low PSA at age 60 you are unlikely to benefit from any subsequent PSA test, because your risk of metastasis or death from prostate cancer is extremely low," said lead researcher Dr. Hans Lilja, an attending research clinical chemist at Memorial Sloan-Kettering Cancer Center in New York City.
Many studies that have reached the same conclusion have not followed the men long enough to determine whether or not additional screening has a benefit. This study, however followed the men for 25 years, until they reached 85, Lilja said.
Interestingly, the researchers measured PSA from frozen blood samples. "This is pretty unique," he said.
The report is published in the Sept. 14 online edition of the BMJ.
For the study, Lilja's team looked at blood samples from almost 1,200 men who were born in 1921. Between 1981 and 1982, these men had blood samples taken and frozen as part of the Malmo Preventive Project in Sweden. The men were followed until they reached age 85 or died.
The team found that PSA at age 60 was a good predictor of which men were at risk for prostate cancer.
The group found that of the 126 men diagnosed with prostate cancer, 90 percent of deaths from the cancer were among the 25 percent of men with the highest PSA levels when they were 60.
According to the study, men with a PSA level above 2 ng/ml at 60 may be at increased risk of aggressive prostate cancer and should be screened regularly.
However, men with a PSA level below 1 ng/ml have only a 0.2 percent chance of death from prostate cancer. Men with a PSA below 1 ng/ml at 60 made up about half of the men in the study and were at a low risk of prostate cancer death.
And while some men with a low risk of prostate cancer may actually develop the disease, it is not likely to be symptomatic or shorten their life by the age of 85, the researchers noted.
"The limitation of the study is that it is based on one population," Lilja said. "We would certainly want to have another corresponding population with a similar finding."
Prostate cancer expert Dr. Anthony D'Amico, chief of radiation oncology at Brigham and Women's Hospital in Boston, said that "the study's conclusion should be that if you live till age 60 and you have not been diagnosed with prostate cancer and your PSA is less than 1 nanograms per milliliter, then your risk of getting prostate cancer is quite small."
"But that's a big if," he said. "What do you say to men who are 45 or 50?"
D'Amico believes that men should have their PSA checked before the age of 60. "Then at 60, if you PSA is less than 1 nanograms/milliliter, then you might be OK," he said.
Men whose PSA is higher at 60 may need a biopsy to check for cancer, he added.
A study published in the Sept. 13 online edition of Cancer found that, in many men 55 to 74 with low PSA levels, further screening and early detection of prostate cancer offer virtually no benefit.
However, this study followed men for only nine years, which is too short a time to draw any definitive conclusions about the need for PSA screening, D'Amico said.
Prostate cancer remains the most commonly diagnosed cancer and the third leading cause of cancer deaths among men in Western countries, but most men with the disease won't die from it. In the United States, a man has about a 15.8 percent chance of being diagnosed with prostate cancer, but the risk of dying from it is only about 2.8 percent, the researchers noted.
The American Cancer Society still recommends that men at high risk for prostate cancer and those 50 and over talk with their doctors about the risks and benefits of screening. However, the cancer society stresses that in some cases -- such as men over 50 who are not expected to live for another 10 years -- such tests should not be offered because they will likely cause more harm than good, with treatments that can cause "unpleasant side effects," such as incontinence and impotence, which greatly affect the quality of men's lives.
For more information on prostate cancer, visit the American Cancer Society.
SOURCES: Hans Lilja, M.D., Ph.D., attending research clinical chemist, Memorial Sloan-Kettering Cancer Center, New York City; Anthony D'Amico, M.D., Ph.D, chief, radiation oncology, Brigham and Women's Hospital, Boston; Sept. 14, 2010, BMJ, online
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