A new review of the evidence on screening for prostate cancer has found that for most men, the potential harms outweigh the gains, leading to the recommendation that routine testing should be avoided.
The study, published in the scientific journal BMJ looked at five randomized controlled trials involving more than 721,000 men and concluded that, at best, screening for prostate cancer via the prostate-specific antigen test (PSA) leads to a small reduction in disease-specific mortality over ten years but has no effect on overall mortality.
“Clinicians and patients considering PSA-based screening need to weigh these benefits against the potential short and long term harms of screening, including complications from biopsies and subsequent treatment, as well as the risk of over-diagnosis and over-treatment,” say the study’s authors, who advise that men at higher risk of prostate cancer death, due to family history or certain genetic traits, for example, may be more likely to choose PSA testing having discussed the issue with their doctor.
Prostate cancer is the most common form of cancer among Canadian men aside from non-melanoma skin cancers, according to the Canadian Cancer Society, which reports that in 2017, 21,300 men were diagnosed with prostate cancer and 4,100 men died of the disease, representing ten per cent of all cancer deaths in men for 2017.
The most common test for prostate cancer is the PSA, which measures tissue inflammation yet can sometimes result in false positives, as reasons other than cancer (infection or normal enlargement of the prostate with age, for example) can produce a positive result.
Once a positive test has been produced, a biopsy often follows, which brings with it its own set of potential risks such as bleeding, infection and urinary incontinence. The issue is further complicated by the fact that for most men with prostate cancer, the tumour grows at such a slow pace that they’re more likely to die of other causes before symptoms of the cancer arise.
In 2014, the Canadian Task Force on Preventive Health Care reviewed the evidence and international best practices and concluded that for men under the age of 55 and over age 70 the PSA should not be used, while for men between 55 and 69, the recommendation was also to not screen but that physicians should discuss the potential benefits and harms of the test with their patients.
“Available evidence does not conclusively show that PSA screening will reduce prostate cancer mortality, but it clearly shows an elevated risk of harm. The task force recommends that the PSA test should not be used to screen for prostate cancer,” said Dr. Neil Bell, chair of the prostate cancer guideline working group of the Canadian Task Force on Preventive Health Care.
The BMJ study concluded that screening of lower risk patients resulted in one less death from prostate cancer per 1000 men screened over ten years, while biopsy and treatment were estimated to result in one more out of 1000 men hospitalized for sepsis, three more requiring pads for incontinence and 25 more reporting erectile dysfunction.