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THE HIGHLY contentious issue of screening for prostate cancer is back in the news after the publication of a large study looking at the effects of prostate-specific antigen (PSA) testing on disease-related mortality rates.
The CAP Trial – involving almost 600 GP practices across the United Kingdom and around 400 000 asymptomatic men aged 50–69 years – compared the outcomes of patients who were invited to have a one-off PSA test with a control group who were not. Around 40% of the men in the intervention arm took up the offer of a test.
After 10 years of follow-up, more cases of prostate cancer were diagnosed in the screened group (4.3% v 3.6%), but there was no difference between the two groups in the number of men who died from prostate cancer. The reason, the researchers say, is that most of the extra cancers picked up in the screened group were of low grade (Gleason Grade 6 or lower) and were therefore unlikely to lead to death. The study findings mirror those of other large trials of PSA screening, which have reported rates of overdiagnosis (detection of disease that would not affect a man in his lifetime) of around 50%.
“The findings do not support single PSA testing for population-based screening,” the study authors concluded.
In an interview on Radio National’s Health Report, lead author Richard Martin, a professor of Clinical Epidemiology at the University of Bristol in the UK, described PSA testing as “a blunt tool”. He said that what was really needed was “a better method of identifying aggressive tumours that will harm men”.
Could this study, and others like it, herald the end of PSA testing in asymptomatic men? That seems most unlikely, for a number of reasons.
One is that PSA testing is firmly entrenched in the Australian medical landscape, as shown in a just-published study in Nature Scientific Reports. The NSW research, based on a cohort from the 45 and Up study, found that over half of asymptomatic middle-aged and older men had had a PSA test within the 3-year study period, despite there being no national screening program for prostate cancer.
Second, the Urological Society of Australia and New Zealand (USANZ) remains a firm advocate for the test. In a media release in response to the new study, it says the PSA test “still offers the best hope for beating prostate cancer” and says that there are steps that can be taken to minimise any potential harms.
Shomik Sengupta, a professor of Surgery at Monash University and USANZ’s UroOncology Advisory Group Leader, says the results of the latest study aren’t particularly surprising.
“It’s reinforcing what’s already been found, which is if you do PSA screening you turn up a lot of low grade cancers, and that’s not the group you necessarily need to treat. Nowadays, we would put these men in a surveillance program. The truth is PSA testing is happening, it’s out there, and inappropriate testing does occur. But we do have well developed guidelines in Australia, which suggest that it can be done in men aged 50–70 years, if the patient wishes it and if he has been appropriately informed by his GP of the potential benefits and harms.”
But the guidelines could also be seen as an exercise in buck-passing, putting the onus on the layman patient to make a decision, or having to rely on the recommendations of an individual GP who may have his or her own idiosyncratic take on what has become a highly partisan issue. Professor Sengupta says that he personally thinks it’s a good idea for asymptomatic men in the target age group to be tested.
“It’s imperfect, but it’s still the best way to pick up prostate cancer. What I think needs to happen is in the step after that, when we try to identify the cancers that need treatment, as distinct from the low risk ones.”
He says that one promising development is the increasing use of magnetic resonance imaging (MRI) as a tool for identifying which cancers need treatment.
“The future of this may well be that if the MRI is good enough, the men who won’t need treatment won’t necessarily have to undergo a biopsy. If they’re in the normal-appearing range, we’ll keep the patient in follow-up, but he won’t have a diagnosis of prostate cancer. He’ll just have something that we need to keep an eye on. That could remove some of the psychological burden of being diagnosed with a cancer.”
Ultimately, Professor Sengupta says, the way to minimise harms and maximise benefits is to perform PSA testing appropriately, with the appropriate safeguards, and do the follow-up.
In that regard, there may be further work to do, judging by the findings of the aforementioned 45 and Up study. The authors of that study found high levels of inappropriate testing: 41% of men in their 40s, 55% of men in their 70s and 30% of men aged over 80 years had had a PSA test within the study period. Non-clinical factors influencing the odds of having had a PSA test included frequency of GP visits, socio-economic group and marital status.
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I have concern about this study for a number of reasons.
I ask those doctors who are against testing how they propose to decrease the death rate from PC.
The PSA test is not perfect but it is the only one available at present.How many years have we been saying we need a better test?
Using mortality rates as an end point for this sort of study has limitations. The quality of life for those found to have any grade of cancer is equally important.Those found to have advanced cancer may have their disease modified for a better life and are better informed for planning their lives.Those with low grade cancer are forewarned and can be treated if necessary.
The figures suggest that after screening the majority of men found with PC will need treatment albeit for some that will be delayed.
Many have suggested that GPs should discuss all the options after explaining the PSA test to men. Does that happen? Does it work? Isn’t it information overload for men? One would need skill to avoid introducing bias in the discussion.
John Trollor PC survivor,Support Group Leader and retired doctor.
It’s not surprising that the Urological Society of Australia and New Zealand (USANZ) remains a firm advocate for the PSA test as they have most to gain from it.
Reminds me of the way the orthopaedic surgeons continued to advocate for arthroscopies even with the mountain of research against this procedure.
There are many specialists who do the right thing by the evidence and their patient’s best interest, but when there’s strong financial self-interest, you do wonder what’s really going on.
A very difficlult area .Eventually we require more precise pathology & radiology tests for prostate cancer.
This study is just another in a long line that fails to show that PSA screening saves lives from prostate cancer. As such there is still no good evidence that PSA screening makes any difference to the risk of dying from prostate cancer other than in the 2 countries with a positive trial (Sweden and the Netherlands). The only difference is that this study is one of the most powerful but in spite of that still failed to detect a reduction in risk of dying from prostate cancer.
Get PSA screening and consequent treatment if you like but don’t expect it to make a difference to your risk of dying from prostate cancer.
Low grade or high grade cancer is still cancer all the same. A woman presenting with CIS of the cervix is treated with the vigor it deserves.
Part of What we need to research on
1is . the efficacy of our follow up and management upon detecting a rising PSA
2. Factors contributing to faster progression of disease in each grade and population and advice on mitigation
In our setting where follow up is eratic and risk is high I would still advocate for PSA screening
I used serial PSA tests ( combined with free PSA ) when in practice, and was more interested in rate of increase (if any) than a single number.
I do not think this study really contributes much that is new.
The problem is the tool (s) is not accurate enough, MRI may not be the critical tool either to determine the likelihood of a cancer diagnosis- Do we have enough experience yet to determine how accurate MRI is and where it sits in the diagnostic paradigm?. (personal bias here)
As a GP I worry greatly over the blokes who, after considered discussion at their health check, decide not to have the test based on this current position… where will they be in 10 years, just as I worry that the blokes who do turn up a positive (PSA or DRE) are then on a potentially dangerous and potentially inaccurate path that may not ultimately offer them the cure they seek.
I yearn for a more accurate set of tests than we have today.
Statistical probabilities are a poor substitute for the GP-heartache at a late diagnosis and the subsequent discussions to square up with the patient- why are we here……
The whole area is a minefield for GP’s and patients no matter how careful.
What do you tell a patient who presents with bone pain 5 or 10 years after a radical prostatectomy?
If a PSA is raised and an assessment is made that the cancer is low grade and statistically you fall into the watch and wait group.
So 5 or 10 years later when you present with bone pain, do you tell the patient that statistically it was correct to watch you. Sorry about the bone secondaries, we can keep you comfortable until you die in the near future.
You must appreciate that for the past 5 or 10 years we saved you from the POSSIBILITY of being in continent or impotent ( and probably living another 10 or 20 happy successful life)
I took the choice aged 60 and had a radical prostatectomy and am still working aged 84 . So my sex life went at 60, but I think most 60 to 80 year olds don’t have a very active sex life in any case, unless they are doing a bit on the side,
there are effectively no men asymptomatic of any prostate symptoms at age 60. So where do you want to draw the line in who should get a PSA test and who not?
” It assists avoiding the early death of men with serious pathology.”
The problem is, this is a claim without general evidence. If it was true then it would show up in most RCTs, not just 2 in 2 countries out of many.
The PSA test has taken a beating in recent years. Is it a surpise that assessing a single PSA in men of more advanced age without any framework for understanding the results leads to marginal outcomes?
Gleeson 6 prostate cancers and indolent in-situ cancer are not the issue here. It’s the 7-8 we don’t want to miss. Just as every breast cancer deserves treatment appropriate to it’s pathology diagnosis, so does prostate cancer. The concept that most prostate cancers are low grade may be close to true in older men, but in the 40-60 age range a raised PSA may be lifesaving.
Invasive or expensive imaging investigation does not have to follow one raised PSA result. A repeat test with similarly or more abnormal PSA a couple of months later is a logical trigger to look further.
The PSA is not a diagnostic test and anxiety created via lack of communication is not the fault of the test.
Stated another way, should we stop ordering lipid profiles and blood glucose as part of a preventive health assessment because they do not confirm a diagnosis or dictate management accurately? Or should we only order one test ever? How do we counsel patients about the anxiety caused by an alcohol history or a blood pressure check? Should we advise women that mammography is less likely to diagnose their breast cancer before it is no longer local disease, than PSA is in men?
Medicine is armed with tools of varying value. In general practice, the PSA test assists in the detection of prostate cancer. It assists avoiding the early death of men with serious pathology. It’s not a bad test.
Having been shown my high grade prostate cancer by a radiologist on MRI done for a pas over 10 that disappeared after antibiotics I think it’s important to realise it’s NOT a totally accurate diagnostic tool.
Still no demonstration that PSA screening and followup saves lives from prostate cancer generally, except in 2 isolated countries and no evidence of a reduction in overall mortality anywhere. This time after a very large trial failed to provide such a demonstration.
This won’t stop the shameful amount of ongoing overtreatment in Australia: http://medicarestatistics.humanservices.gov.au/statistics/do.jsp?_PROGRAM=%2Fstatistics%2Fmbs_item_standard_report&DRILL=ag&group=37210%2C+37211&VAR=services&STAT=count&RPT_FMT=by+time+period+and+state&PTYPE=calyear&START_DT=199401&END_DT=201712
If we start throwing MRIs at everyone with suspected prostate cancer on a PSA this will result in huge increases in health costs, not to mention biting into the world’s very limited resources of helium gas which are essential for cooling the magnets that run the machines. I’d really want to see that it had a proven benefit to the patients, not just a benefit to the careers of the urologists.
Improved MRI studies indicate this investigation should now be an essential for the urologist to ensure his treatment of the enlarged prostate ,with or without radiotherapy, is appropriate and curative.
It is difficult to see the external validity of a study in which only 40% of ‘invitees’ are given a single PSA test and followed for only a decade, or how it managed to get past peer review into publication. So poor a study into breast cancer screening would never make it through that process.
correction, line 6 should read ‘asymptomatic prostate cancer’
From cadaver studies, the incidence of prostate cancer is incredibly high, if one looks hard enough – greater than 50% in men aged 70yrs. The better our tools for looking for prostate cancer, such as MRI; the more we will find and we will need to be treating or tracking a large percentage of the older male population. This is despite the increased anxiety for these men as they repeat test after test.
I think all men need to look at the bigger picture – they will not live any longer if they look for symptomatic prostate cancer. In all likelihood they will be worse off due to 50% incidence of overdiagonsis with resultant effects of biopsy, surgery, radiotherapy; not to mention increase constant anxiety.