“We project about a 25 to 30 per cent reduction in the risk of prostate cancer deaths when PSA screening is used,” said Ruth Etzioni, a public health researcher with the Fred Hutchinson Cancer Research Centre, in Seattle, Wash.
Etzioni was part of a team from the University of Michigan and the National Cancer Institute that used a new mathematical model to re-analyze data from two major clinical trials: the European Randomized Study of Screening for Prostate Cancer (ERSPC) and the U.S.-based Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial (PLCO), which offered conflicting results.
“It was clear from the European trial that there appeared to be some benefit, but it was much less clear from the U.S. trial.”
After re-analyzing the data from both trials, Etzioni says the U.S. and European results were similar; both studies showed benefits.
Still, critics of the test maintain the PSA causes more harm than good, because it led to over-diagnosis and over-treatment.
“The benefit of this screening is really very small,” said Dr. James Dickinson, a public health researcher with the University of Calgary.
In 2014, Dickinson was part of an expert panel that released guidelines recommending the PSA not be used to routinely screen for cancer.
“It really doesn’t change our opinion because on the Canadian Task Force, when we looked at this, we primarily focused on the results of the European trial, so this merely confirms that same opinion.”
Current guidelines from the United States Preventive Services Task Force (USPSTF) also recommend against PSA screening for prostate cancer, because the evidence for the test showed very low probability that it would reduce the risk of dying from prostate cancer.
In response to the controversy, Prostate Cancer Canada has called for “smart screening,” a personalized approach where men are tested to establish a baseline number. That initial measure is then compared to subsequent tests to see if changes are detected. If changes are detected, patients can work with their physicians to consider biopsies, MRIs or rectal exams.
About 23,600 men were diagnosed with prostate cancer in 2014, according to Prostate Cancer Canada. It’s the third-leading cause of death in Canadian men.