The findings oppose current guidelines from the United States Preventive Services Task Force (USPSTF), which advise against prostate-specific antigen (PSA) screening for prostate cancer due to lack of evidence that it lowers the risk of death from the disease.
According to the review authors - led by Ruth Etzioni, Ph.D., of the Fred Hutchinson Cancer Research Center in Seattle, WA - their findings suggest that guidelines for PSA screening may need to be reviewed.
The researchers recently reported their results in the Annals of Internal Medicine.
Prostate cancer is the most common cancer among men in the U.S., after skin cancer. This year, it is estimated that around 161,360 new cases of prostate cancer will be diagnosed in the country, and approximately 26,730 men will die from the disease.
Men aged 65 and older are at greatest risk for prostate cancer, and the average age of diagnosis is 66 years.
PSA screening for prostate cancer
The PSA test is one of the predominant tests used to diagnose prostate cancer. It assesses levels of prostate-specific antigen in the blood, which is a protein produced by cells in the prostate gland.
The American Cancer Society (ACS) state that the majority of men without prostate cancer will have a PSA level under 4 nanograms per milliliter. Men with a PSA level of between 4 and 10 nanograms per milliliter have a 1 in 4 chance of having prostate cancer, while a PSA level over 10 is associated with a 50 percent chance of developing the disease.
However, there are many other factors that can influence a man's PSA levels, including urinary tract infections and certain medications. As such, research has indicated that PSA tests run the risk of yielding false-positive results for prostate cancer, which may put men through unnecessary stress and treatment.
According to the USPSTF, "There is convincing evidence that PSA-based screening for prostate cancer results in considerable overtreatment and its associated harms."
What is more, they state that existing studies have demonstrated only a "very small" decrease in death from prostate cancer as a result of PSA screening.
Taking all evidence into account, the USPSTF "recommends against PSA-based screening for prostate cancer."
USPSTF guidelines 'should be reviewed'
Dr. Etzioni and colleagues note that the USPSTF guidelines for PSA screening were largely based on the results of two studies: the European Randomized Study of Screening for Prostate Cancer (ERSPC) and the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (PLCO).
While results from the ERSPC suggested that PSA screening is linked to a reduction in prostate cancer-specific mortality, results from the PLCO showed that the screening offers no such benefit.
On reviewing these two studies with a mathematical model, however, the researchers found that they both demonstrated evidence of a significant reduction in prostate cancer death as a result of PSA screening.
For each study, the researchers compared the risk of prostate cancer death between men who did and did not undergo PSA screening.
Using their mathematical model, the team was able to account for differences in how each study was implemented, as well as any variations in practice settings.
When accounting for these differences, the researchers found that both studies showed that PSA screening is associated with a significant reduction in the risk of death from prostate cancer.
Based on these findings, the team suggests that current guidelines advising against screening for prostate cancer should undergo review.