Why is PSA test so controversial?

Echo Dale Regional Park in Medicine Hat, AB. (Dr. Noorali Bharwani)
Echo Dale Regional Park in Medicine Hat, AB. (Dr. Noorali Bharwani)

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

  1. 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).
  2. 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).
  3. 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.
  4. 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.
  5. 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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Is PSA test a public health disaster?

Sand art on the beach in Albufeira, Algarve, Portugal. (Dr. Noorali Bharwani)
Sand art on the beach in Albufeira, Algarve, Portugal. (Dr. Noorali Bharwani)

Dr. Richard J. Ablin, PhD, DSc (Hon), first discovered prostate-specific antigen (PSA) in 1970. At the time, Ablin and colleagues were trying to identify an antigen that was specific to prostate cancer.

PSA test was introduced in the United States around 1990 for early detection of prostate cancer.

In 2010, Ablin called the PSA test a public health disaster. So, what went wrong? Why do we still order PSA test?

Let us start from the begining.

All men have a prostate gland. The gland produces some of the ingredients of semen. It sits just in front of the rectum and below the bladder. It can be felt on a rectal examination. It weighs about 30 grams. It is vital for the proper functioning of the male reproductive system.

One of the enzymes in prostatic fluid is prostate-specific antigen (PSA). After ejaculation, PSA makes thickened semen runnier, helping sperm travel through it more easily. Thus, increasing their likelihood of successfully fertilizing an egg.

Why PSA test can do more harm than good?

Reviewing some literature, I found Ablin, who is now a research professor of immunobiology and pathology at the University of Arizona College of Medicine and the president of the Robert Benjamin Ablin Foundation for Cancer Research, has said, “in approving the procedure (PSA test), the Food and Drug Administration relied heavily on a study that showed testing could detect 3.8 per cent of prostate cancers, which was a better rate than the standard method, a digital rectal exam.” Was that a wise decision?

PSA test is costing health care system billions of dollars. It is estimated that each year, some 30 million men undergo PSA testing in the US, at a cost of $30 billion. Ablin has said the test is hardly more effective than a coin toss. The PSA test cannot distinguish between the two types of prostate cancer – the one that will kill you and the one that won’t.

The American Cancer Society now urges more caution in using the test and the American College of Preventive Medicine has concluded that there was insufficient evidence to recommend routine screening. Then why do we still use it?

“Many doctors have distorted perceptions of the value of medical tests,” says Dr. Miriam Shuchman in the Canadian Medical Association Journal (CMAJ February 04, 2019). And patients have the same distorted perceptions.

In 2014, the Canadian Task Force on Preventive Health Care recommended against using the PSA test to screen for prostate cancer in healthy men, concluding that it results in substantial harms via biopsies and surgeries that can lead to infections, impotence or urinary incontinence, and does not save men’s lives.

Canadian and American task forces recommend that any man considering screening for prostate cancer should have a chance to first discuss the pros and cons with a doctor. The CMAJ article says that if men knew what the risks were associated with PSA testing and how slim to nonexistent the benefits are, no man in his right mind would get tested.

Considering PSA screening results in only a 0.1 per cent reduction in death from prostate cancer, the harms associated with screening outweigh the benefits for most people.

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For Men Prostate Problems are Almost Inevitable

A gentleman said, “Doc, how come you have not written about prostate problems lately?” He was right. Sometimes I feel I have written about a subject recently but when I look back at my list on the computer, I find time does go by fast. So, here is some information about prostate problems.

On a personal note, I am proud to say that this is my 400th column. I appreciate all the feed back and encouragement I receive from readers from all walks of life. Not only I enjoy writing but I learn a lot myself when I do all the research for my articles. I have learnt to take care of my health better thanks to these columns.

Ok, let us get back to our subject.

“Prostatic disease eventually affects almost all men; benign prostatic hypertrophy or hyperplasia (BPH) is an inevitable part of aging,” says an article in the Canadian Medical Association Journal (CMAJ June 19, 2007).

Do we need to worry about prostatic hypertrophy or hyperplasia which in simple terms means prostatic enlargement? Sure, we have to worry. Who knows, it could be malignant. Although prostatic enlargement eventually affects almost all aging men, not all men suffer from prostatic cancer. The lifetime risk of diagnosis of prostatic cancer is 18 per cent and death from prostatic cancer is three per cent.

Enlarged prostate gland has several effects. These include difficulty with voiding urine and blood PSA levels may go up. Other complications are urinary retention, urinary bleeding, bladder stones, recurrent urinary tract infections and renal failure. These effects become progressively worse requiring frequent medical attention and rising PSA requires multiple tests to rule out prostate cancer.

About 20 years ago, the standard treatment for benign enlargement of prostate gland was surgery. Now, patients with mild symptoms do not need any treatment. Patients with moderate symptoms are treated with medications. These medications have shown to improve the flow of urine and improve the quality of life. Do these medications prevent complications of BPH? Studies have shown that this is possible.

The two major classes of drugs used to treat BPH are: a) alpha-blockers like doxazosin relax smooth muscle fibers of the bladder neck and prostate gland to reduce prostatic obstruction, b) five- – reductase inhibitors like finasteride decrease levels of testosterone in the prostatic gland itself but do not affect the systemic testosterone level. This leads to reduction of the prostate gland by 20-30 per cent.

With -blockers, patients experience relief of symptom within two weeks of starting the medication, compared with several months with finasteride. Researchers have found that doxazosin and finasteride slowed down the growth of BPH compared with placebo; the combination therapy was significantly more effective than either drug alone.

The CMAJ article says that the Medical Therapy of Prostatic Symptoms study showed that:
-BPH is a progressive disease
-progression can be prevented by medical therapy
-patients at risk for progression can be readily identified by PSA level, prostatic volume and symptom severity
-and the combination of finasteride and doxazosin is more effective than either alone in preventing progression, particularly in high-risk groups.

Are there any side-effects to these medications?

The article says that clinically significant side effects, mainly postural hypotension (low blood pressure), were infrequent and they led to cessation of therapy in 18–27 per cent of the men involved in the study. Side effects that occurred were minor and related mainly to sexual function.

Patients treated with finasteride had significant benefit with improvement in urinary symptoms. There was also an added advantage in that the finasteride-treated patients saw reduction in the overall risk of prostate cancer by 25 per cent – a rate almost unheard of in the field of cancer prevention, says the CMAJ article. The authors of the article say, “Because PSA levels are reduced in men with BPH who are taking finasteride, rising PSA findings are more likely to be caused by prostate cancer. Taking this drug may therefore provide a diagnostic advantage as well.”

The article poses the question: Should selected patients now be offered finasteride to lower their risk of developing prostate cancer and BPH progression?

“The answer, based on these trials, is unequivocally yes,” conclude the authors of the CMAJ article.

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Controversial Role of PSA in Early Detection of Prostate Cancer

Controversy regarding the use of PSA (prostate-specific-antigen) in early detections of prostate cancer continues with the recent publication of an article in the New England Journal of Medicine (NEJM).

Prostate cancer is the most frequent cancer and the second leading cause of death from cancer in men, exceeded only by lung cancer. In 2008, an estimated 24,700 men were diagnosed with prostate cancer and 4,300 died of the disease.

The walnut size prostate gland lies below the urinary bladder in front of the lowest inch of the rectum, through which it can readily be felt on digital rectal examination (DRE). The gland has an important role in the proper flow of urine. It also provides the proteins and ions that form the bulk of the semen. In conjunction with other smaller glands in the vicinity, the prostate gland produces secretions that serve to lubricate the reproductive system and provide a vehicle for storage and passage of sperms.

Once upon a time, “the old finger” i.e. DRE was the only crude way to pick up early prostate cancer. Although DRE has a cancer detection rate of only 0.8 to 7.2 percent, it remains an important test that can be done easily in a doctor’s office. It also checks for anal and rectal tumours.

The PSA test was introduced in North American medical practice by the end of 1980s. PSA was expected to replace the embarrassing and uncomfortable DRE. And it was promoted as an ideal test for screening and early detection of prostate cancer. But this hope has not materialized. PSA blood test has a false positive rate of 20 to 50 percent and false negative rate of 25 to 45 percent. That means 30 to 50 percent of the time the test is wrong.

The editorial in the NEJM says, “In the United States, most men over the age of 50 years have had a prostate-specific–antigen (PSA) test, despite the absence of evidence from large, randomized trials of a net benefit. Moreover, about 95 per cent of male urologists and 78 per cent of primary care physicians who are 50 years of age or older report that they have had a PSA test themselves, a finding that suggests they are practicing what they preach.”

Recent clinical trials have shown that PSA screening without DRE was associated with a 20 per cent relative reduction in the death rate from prostate cancer at a median follow-up of 9 years, with an absolute reduction of about 7 prostate cancer deaths per 10,000 men screened. Critics say that this is at best a modest effect on prostate cancer mortality and the benefit comes at the cost of substantial over-diagnosis and over-treatment. There is net harm compared with potential benefits.

Experts agree that PSA testing is an imperfect screening tool. They say the test is as effective as programs such as mammography for breast cancer and fecal occult blood testing for colorectal cancer.

The Canadian Cancer Society recommends that men aged 50 and older discuss the benefits and risks of PSA testing with their physician, and the society does not plan to change its recommendation based on recent research.

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