Prostate cancer remains the most commonly diagnosed non-skin cancer among Canadian men and is the third leading cause of cancer-related death.
The natural history of prostate cancer ranges from a potentially inconsequential course to a fatal disease. Doctors continue to grapple with the question of how to identify those with clinically important disease while avoiding overdiagnosis and overtreatment, says an article in the Canadian Medical Association Journal (CMAJ October 24, 2022 194) written by Kikachukwu et al.
History of PSA (prostate-specific antigen) test
T. Ming Chu, PhD, DSc, Chair Emeritus of Diagnostic Immunology Research and Professor Emeritus of Urologic Oncology, led the research in the 1970s that resulted in the discovery of PSA and the development of the PSA test.
PSA test was originally approved by the FDA (Food and Drug Administration in U.S.) in 1986 to monitor the progression of prostate cancer in men who had already been diagnosed with the disease. FDA approved PSA as a screening test seven years later.
Even after 30-years, why is PSA screening test controversial?
Using the PSA test to screen men for prostate cancer is controversial because it is not yet known for certain whether this test actually saves lives. Moreover, it is not clear that the benefits of PSA screening outweighs the risks of follow-up diagnostic tests and cancer treatments.
The Canadian Task Force on Preventive Health Care (CTFPHC) recommends against routine PSA screening for men of all ages, but states that the greatest benefit from screening is likely in those aged 55–69 years.
The guideline identifies and reports the increased risk of prostate cancer among Black people, but does not provide specific guidance on managing this increased risk. The new guideline was published online on October 27, 2022 in the Canadian Medical Association Journal (CMAJ).
Research from the United States and Europe has shown the incidence and lifetime risk of developing prostate cancer among Black people are more than double than among their white counterparts (CMAJ October 24, 2022 194).
There is no doubt prostate cancer screening can help identify cancer early on, when treatment is most effective. But some prostate cancers are slow growing and never spread beyond the prostate gland. This is where the dilemma is.
Some other points about PSA test
- False positive results and overdiagnosis. This happens quite often with PSA testing and only about 1 in 4 abnormal results is due to cancer. A false-positive result can lead to unnecessary testing that is more invasive, such as repeated biopsies. It can cause unnecessary anxiety and distress. (CCS – Canadian Cancer Society website).
- A false-negative result means that the test shows the PSA level is normal even though prostate cancer is present. Not all prostate cancers cause a high PSA level. PSA testing misses about 15 per cent of prostate cancers (CCS).
- Most medical organizations encourage men in their 50s, men age 45 who have family history of prostate cancer or are Black individuals to discuss the pros and cons of prostate cancer screening with their doctors.
- Most organizations recommend stopping PSA tests around age 70. Men at age 70 and over have the highest incidence of prostate cancer over-diagnosis and several studies have suggested that screening in this age group is likely not beneficial.
- In most men with prostate cancer, the tumour grows slowly, and they’re likely to die of another cause before the prostate tumour causes any symptoms. The prognosis for most prostate cancers is good, with a 10-year survival rate of 95 per cent.
Questions remain – Who should get PSA test, at what age to start (45, 50 or 55) and how to manage patients with elevated PSA test results?
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