Men, perhaps it's time to schedule a prostate screening exam with your doctor! New results from two eminent prostate cancer screening trials show that this procedure does make a difference in lowering death risk.
PSA and the prostate
Prostate cancer represents a huge health risk – it is the most common form of cancer in men. In 2013, nearly 2.8 million men were living with prostate cancer in the US. Fortunately, prostate cancer has one of the better 5-year survival rates at 98.9 percent.
Measuring the level of prostate-specific antigen (PSA) is a minimally invasive method to predict cancer risks. However, tests that use this biomarker have been criticized for its diagnostic power.
PSA levels for healthy men are usually less than 4 nanograms per milliliter (ng/mL) of blood. Men with PSA levels between 4 and 10 ng/mL may have a 25 percent risk in prostate cancer, according to the American Cancer Society. And those with PSA levels higher than 10 ng/mL could have as high as a 50 percent chance of prostate cancer.
However, according to the United States Preventative Services Task Force (USPSTF), having more or less PSA than that range doesn’t guarantee cancer or no cancer, respectively. Furthermore, PSA level cutoffs are not standardized, which contributes to increased cases of false negatives and false positives. At least that’s why the USPSTF currently recommends against PSA screening. "There is convincing evidence that PSA-based screening for prostate cancer results in considerable overtreatment and its associated harms,” per the USPSTF.
New evidence to consider
But the evidence on which the USPSTF guidelines were based may have not been analyzed properly, say researchers from the University of Michigan and the National Cancer Institute.
The researchers reviewed the two critical PSA screening studies that informed the USPSTF guidelines. The first is the European Randomized Study of Screening for Prostate Cancer (ERSPC), and the second is the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (PLCO).
Previously, results from the ERSPC suggest PSA screenings do reduce death risk from prostate cancer. However, results from the PLCO trial suggest PSA screenings had no effect on prostate cancer mortality.
But there are differences between the trials that were not taken into account. For example, the two trials had different implementations and settings. Using a new mathematical model, the team teased apart the differences between the two trials, leaving behind data that no longer conflicted with other. Specifically, the model suggests PSA screening does reduce death from prostate cancer.
The authors hope the new conclusions will spur a discussion on PSA screening guidelines that could help prostate cancer detection while not put patients at risk for overdiagnosis.
Additional sources: American College of Physicians via Science Daily, MNT