Art credit: Vimeo
As Movember has come to a close, and men flaunt or shave the facial hair they have grown, there is something people should know — prostate cancer screening is ineffective and can do more harm than good.
Movember is a global charity that raises money for men’s health. One of its key areas for fundraising and awareness is to advocate for prostate cancer testing with a PSA test.
As a family physician and public health researcher, I am not getting a prostate cancer test: Neither a rectal examination nor a PSA blood test.
As a man of a certain age, I am likely to already have prostate cancer, and I know that suffering and even dying from this cancer is on the list of possible fates that await me. My choice is not because I have my head in the sand. It is because, after studying the evidence, I know that a test will likely not improve my outcome.
In recent years, the pressure on men to be screened for prostate cancer has been mounting, with organisations encouraging us to “know your number.”
“It is only a simple blood test,” after all.
Prostate Canada says that one in seven men will have prostate cancer. With the help of screening and then curative surgical treatment, Movember and Prostate Canada claim that prostate cancer now has a cure rate of over 97 per cent.
Sadly, these claims give a very false impression of the reality.
Prostate cancer is indeed very common, but more so in countries that screen a lot, like the United States and Canada. Death rates have less variation. Studies that examined normal men at different ages found many men have small amounts of what looks like cancer in their prostate. Over 30 per cent of men in their 60s have some prostate cancer cells, and in their 80s, over half do. But even if they are not treated, only about three per cent of men will actually die of prostate cancer, and most of that will occur at the very end of life, in their 70s or 80s.
If we find cancer many years earlier than we would normally, of course the men will survive five years, though they may still die at the same age as they would have without screening. This is called “lead-time bias.”
Since many prostate cancers grow very slowly many men will die of something else before the cancer can affect them. This is called “overdiagnosis:” Identifying disease that will never be important.
The evidence shows that if we left men alone we would only recognise prostate cancer in perhaps one in 16 men. The cure rate looks high, because we create false alarms and label many men as having cancer that will never affect them.
Screening is not “just a test.” To take this test is to step into a canoe running down a river with wild and unpredictable rapids. Let me explain….
The PSA test is a laboratory measurement with errors: Both false positive and false negative. The threshold for abnormality is not clear. Different authorities recommend different levels, and many vary with age.
For men who test positive, the first investigation is usually a prostate biopsy — a needle is poked into the prostate gland multiple times to obtain samples of the gland, to be examined under the microscope. This procedure can carry infection into the gland, and results in severe infections in one per cent of patients. Sometimes this becomes septicemia (blood poisoning) that damages kidneys and other organs, or kills the man.
The biopsy samples are examined under the microscope by pathologists, who try to predict from their appearance whether this collection of cells is likely to go on to kill the man.
This is difficult: Most cell changes that look like cancer do not develop, spread and kill. Prediction is easier for severe changes than for more frequent minor changes.
Treatment is potentially helpful for the few men with severe changes, but for the majority with minor changes it is unclear how best to proceed.
Treatment varies and can do more harm than good. Some urologists treat all “cancers.” Others follow a newer approach of surveillance, with regular re-testing, and possibly a repeat biopsy. Thus a well man can be converted into a “possible cancer” patient, getting regular tests, and being reminded that he might have a developing cancer. It is not surprising that many such men decide to have surgery, just to get the gland out, and save the anxiety.
Having surgery to remove the prostate is not a benign process. As with any operation there is a risk of complications. Some men will get infections, blood clots and a few will die.
After recovery, many men have urinary incontinence and erectile difficulty. It is hard to know the actual rates since measuring these is difficult: How much dribbling of urine, or how many embarrassing episodes of urgency should be counted to decide it is important? Measurement of all these outcomes is usually only published by the best centres that are willing to publicly describe their outcomes. There is wide variation across Canada: It appears that results are worse for many centres.
Everyone assumes that having the operation for early cancer will cure it.
Yes, it does, for a small proportion of men. The few trials available comparing surgery with not treating prostate cancer show a very small benefit for surgery. If you had an early cancer that would not develop, then the surgery cured you. (But you never needed the cure.)
On the other hand, most men with severe cancer still die despite screening and treatment.
The enthusiasts for PSA screening assert that they are preventing development of advanced prostate cancer. I wish that were true.
Their evidence comes from one project conducted in Europe, where seven centres started running trials on thousands of men aged 55 to 70 years, but only two of the centres showed clear positive results. Even in the trials with positive results, the chance of benefit was small. To prevent each single death from prostate cancer, they had to invite around 800 men. Harms occurred, as over-diagnosis rates were high. And, after 13 years of follow-up, for one less death, six men still died of the disease. So screening does not prevent death from prostate cancer, only reduces it slightly.
Criticism of the trials has also pointed out that these results could be due to the screened men being treated at highly skilled centres, that offered more modern drug treatment. If so, men should simply wait until they get cancer, then obtain high-quality treatment. This choice gives a slightly higher risk of cancer spread, but reduces the chance of over-diagnosis followed by unnecessary treatment.
After the European trial results were published, most evidence-based medical groups including the Canadian Task Force on Preventive Health Care decided that men are more likely to experience harm than benefit from screening. So they warned against screening. Their evidence is summarized in decision aids to assist men to understand the risks and benefits.
Urology Associations have a conflict: their members see men dying miserably from the disease, and naturally want to do everything to stop it. However, they too became more cautious after seeing the trial outcome, and now recommend that men should be informed of the risks before they start down the screening pathway.
The American Urology Association recommends that men under age 55 should not be screened. The Canadian Urology Association was in agreement, but recently lowered the age to 50 years, except in special cases of strong family history, where the risk of cancer is higher. It is not clear how well their members follow these recommendations. Many clearly do not.
The Calgary “Man Van” — a mobile men’s health clinic offering PSA testing — recommends testing from the age of 40 and does not inform men of the uncertainties involved. This organisation is advised by urologists, who clearly do not follow their organisation’s policies. The Movember movement says age 50, and 45 for those at high risk.
And for men with higher risk, because of a strong family history, or slightly raised risk because of African ancestry — we have no clear evidence. We simply do not know whether screening is more or less effective among these men, nor whether their risk starts earlier than other men.
The PSA test has been directly marketed to men. The sponsors are not always clear, but appear to be the manufacturers of the tests, and others who profit from screening. They include companies that make surgical equipment and drugs used to treat cancer, and supermarkets that sell incontinence products. For these generous donors, the more men who are diagnosed, the more product they sell.
Prostate screening organisations have also persuaded many men of goodwill that this is a life-saving activity. And they have enlisted other donors who believe in the movement, often after having had a “cancer” removed, persuaded they have been cured by surgery.
It is difficult to tell such survivors that they likely had unnecessary surgery that caused the risks and complications, while most who have severe cancer still die despite the treatment.
Men die on average six years earlier than women. For young men, injury and violence including road accidents are the commonest cause, often fuelled by alcohol. In midlife up to age 75, cancer is the most important cause of death. After that, cardiovascular disease dominates.
But prostate cancer only comprises 20 per cent of the cancers. Lung cancer is still the most common fatal cancer in men, largely caused by smoking. Indeed more than half of all smokers die of smoking-caused disease, so for them, other causes barely matter.
Many men are obese, have high blood pressure and diabetes (which are often poorly controlled). All these improve with behavioural change: men need to quit smoking, minimize alcohol, eat healthy food and take regular exercise. Even a small increase in activity, such as walking regularly, will make a substantial difference to the effect of these diseases and lower the risk of death. It also helps people feel better.
Thus rather than encouraging “a simple blood test,” it is far better for men to encourage one another to change behaviours. This is likely to have far more value — with fewer negative effects — than doing PSA tests.
James Dickinson, Professor of Family Medicine, University of Calgary