To PSA screen or not to PSA screen? That is the question. Actually, though, maybe that shouldn’t be the question.
A prostate-specific antigen (PSA) test is a blood test that measures the amount of circulating PSA. PSA is a protein made by prostate cells. When the PSA is ‘high’, there is an increased likelihood that it is elevated because of the presence of prostate cancer. Other benign conditions ‑ like infection or benign growth of the gland – can also lead to an elevated PSA.
PSA tests in men with no other signs or symptoms can therefore help detect prostate cancer early. But the tests can also miss cancers (in males whose PSA levels aren’t high), give false positives (in males who have high PSA but no cancer) and cause “over-diagnosis” by detecting cancers that otherwise would never be found or ever put the man’s health at risk.
And so, this mix of benefits and risks has led to some mixed and consequently confusing messages about the use of the PSA test for prostate cancer screening.
In 2012, the US Preventative Services Task Force and the Canadian Task Force on Preventive Health Care (CTFPHC), both issued new guidelines against PSA Screening tests after two large studies suggested that there’s no survival advantage to having PSA screening tests over not undergoing screening. In contrast, a similar study in Europe found that there is a survival advantage in men who undergo PSA screening.
Earlier this year, the US task force who made the initial recommendation against PSA screening revisited their recommendations given the increasing evidence that there may in fact be a more significant survival difference in men that are screened versus those that are not. As a result, the US task force released the following statement: “We are softening our opposition to the PSA test”, and they now suggest every male discuss PSA screening with their physician.
So should you get a PSA screening test? As is usually the case with these kinds of questions, the answer is: that depends.
The problem isn’t the test itself, says Dr. Danny Vesprini, a radiation oncologist and researcher at Sunnybrook.
“We know that the test works in determining elevated PSA levels, which may be a sign of prostate cancer,” he said. “The problem isn’t the test, or the ‘overdiagnosis’ of early prostate cancers; it’s the ‘overtreatment’ of low-grade disease that can be found using this method of screening.”
That’s the peril of the PSA test – what if you get diagnosed with prostate cancer when really you have a very low-grade cancer that will really never go on to cause you any problems or risk your life, and then get treated aggressively for that cancer?
“This really should be a discussion about overtreatment, not about the efficacy of the PSA test,” Dr. Vesprini said. “We know Active Surveillance is an appropriate and effective way to manage low-grade prostate cancer in most men, so we need to educate people about that.”
Active Surveillance is an evidence-based management approach that aims to improve quality of life by reducing aggressive treatment, which can result in side effects including erectile dysfunction, as well as problems with urinary or bowel control.
Patients are carefully monitored on an ongoing basis. Those who are re-classified as ‘higher risk’ over time, based on rapid rise in PSA or grade progression on repeat biopsy, are offered intervention through surgery, radiation or hormonal therapy (or a combination of these treatment options).
“So, we should acknowledge the PSA screening tests will likely over-diagnose men but then we should use Active Surveillance rather than aggressive treatments for the men with low-grade cancer,” Dr. Vesprini said.
Dr. Laurence Klotz, urological oncologist at Sunnybrook, agrees.
“The risk of overtreatment associated with PSA testing can be largely addressed by adopting conservative management, or Active Surveillance, for those men with more favourable cancers,” he said. “This has been demonstrated to be safe in large, long-term studies. The concept is that men found to have aggressive cancers benefit a great deal by early detection, which is associated with a high cure rate. The men found to have non-significant cancers, that don’t pose a threat, can avoid treatment. This combination approach is very effective.”
Males in the high-risk groups – those with a family history of prostate cancer, those of African / Caribbean descent, or males with a BRCA gene mutation – should definitely get PSA screening starting at age 40.
“The best thing every man can do is talk to your doctor about the pros and cons of you as an individual getting the PSA test,” Dr. Vesprini said. “What does it mean for you? What will it mean if you are diagnosed with a low-grade cancer? What are the implications of being diagnosed from a medical, psychological and/or social/economic point of view? Very importantly, what are your risk factors? In a nutshell, ask your doctor about the risks and benefits of the screening as it pertains to you and your value system. For many the risk of ‘overdiagnosis’ is worth it to ensure that they do not go on to develop more aggressive, life threatening disease.”
More resources:
Learn more about BRCA gene mutation.
Familial Prostate Cancer Clinic at Sunnybrook.
