IARC 50th Anniversary Conference
Prostate cancer screening: A north/south comparison in Ireland
Dr Anna Gavin - Queen's University Belfast, Belfast, UK
Prostate cancer is the most common cancer diagnosed in men in Western countries. We know that it has increased rapidly over the last twenty years and we have a lot of debate about whether prostate cancer is actually something that should be screened for and detected early or whether it’s something that we should let sit and run its natural course.
How did you investigate this?
We have a natural experiment that has occurred on the island of Ireland. So these are two separate jurisdictions with separate health services but very similar populations, no difference in genetics, good health services and good cancer registries. We know from the cancer registries that prostate cancer is diagnosed about 50% more often in the south of Ireland than in the north of Ireland. So here we have a situation where through increased PSA testing and prostate biopsy we have many more men diagnosed with prostate cancer in the south of Ireland compared to the north of Ireland.
As a consequence of this, what has happened?
We looked at the deaths from prostate cancer and there’s very little difference in that. So the next thing to look at is what do patients report as the side effects from their treatment. So this is a patient reported outcome study. So we surveyed over 6,000 men and over 3,000, 3,348 in fact, men responded to us. We asked them questions about very sensitive areas – impotence, incontinence – but we also used some instruments about their quality of life and their regret and everything like that about the tests.
What were your findings?
In order to assess this accurately we knew that many more men in the south of Ireland were diagnosed at a younger age with earlier disease and with low comorbidity than in the north of Ireland. So we had to do something, so we looked at the early disease men and we looked at the late disease men separately and compared them for Northern Ireland and the south of Ireland. What we found was that the level of urinary incontinence, which is actually very distressing for men, was 16% ongoing in early disease and late disease in Northern Ireland and in the south of Ireland, no difference. We found that impotence which is ongoing, which is also a very disturbing aspect of the outcomes of treatment, was 56% in early disease men and 68% in late disease men with no difference between the north of Ireland and the south of Ireland. We found that there was very little difference in any of the other measures in terms of health related quality of life. The men from Northern Ireland reported more bowel problems in early disease and more pain in late disease and we think that that’s because they tended to be older and even though we did try and adjust for that maybe we didn’t do it well enough. In the south of Ireland the only difference that we found was that the men from the south of Ireland reported more financial difficulties and that’s perfectly reasonable because they have to pay some of their healthcare. So they were younger men, maybe, who were still working who had this disease and so they were having difficulties financially.
So what we found was that really there was very little difference in the patient reported outcomes from the treatment. We found, though, that there were many, many more men treated in the south of Ireland than in Northern Ireland and so that makes us think that we are over-treating and we have just left an awful lot more men in the south of Ireland with these problems after their treatment for prostate cancer than would have happened had there not been PSA testing.
Within these two groups, how much over-treatment is happening?
We have 50% more cases per head of population in the south of Ireland so there’s an awful lot of men in the south of Ireland who have been investigated, who have been treated for prostate cancer and who have been left with side effects that, had they not been treated, they would not maybe have those side effects. One of the drawbacks is that in the study we didn’t know what the normative level was so we’re going to do that study and we’re going to… So we don’t know, as men get older they do have problems with their urine flow, they do have problems with impotence and so we don’t know what the normal values are and whether they are different between the north and the south but we don’t think they are.
Moving forward, should you investigate and treat less, therefore having less of a burden of impotence and urinary incontinence?
There are better and newer treatments that are less likely to leave side effects with men, so some of the treatments have changed over time so we have to take that into account. But actually men need to know this information when they are having their investigations discussed. So even before they have a PSA test they need to know what the likely outcome is because once they have their PSA test they are on a conveyor belt because they’re either sitting there worrying that they have a raised PSA test and what do I do about it or they are already going for a biopsy and the more biopsies you get the more likely you are to pick up prostate cancer. One of the big risk factors for prostate cancer is having a PSA test.
What message would you give to cancer doctors?
I think cancer doctors are very keen to investigate and treat cancers and the message is to try and get it early. It doesn’t work with prostate cancer because the PSA test is not a screening test that has been shown to be of value in studies. So it’s not sensitive enough, it’s not specific enough. It will pick up a lot of men who have disease that’s not really aggressive or that’s not really going to cause them much harm. So we do need to have this information available for men so that they’re informed when they make their decision.
What about other modalities of testing?
It is important to keep investigating to see are there other modalities. At the minute it’s a PSA test, it’s a digital rectal examination and then that would lead to a prostate biopsy. There are no tests that I’m aware of yet, maybe there are others being developed, that could actually be used better. But if we are going to introduce a new test it has to be done at a population level, it has to be part of a case control study. We would have to wait for some years before we would see its effectiveness in the population.
What are your thoughts on watchful waiting for many of these patients?
The group who were on watchful waiting actually were the group that reported least side effects and so they were still alive. Various studies have shown that actually watchful waiting is something that works well with prostate cancer.
How appropriate is it to treat prostate cancer, given that it is of high aggressivity?
We had some measures from the Gleason score of how aggressive the cancer was and we did take that into account when we were allocating the patients to early stage or late stage disease. There are other studies ongoing that show that actually if you leave men their outcome is very similar to if they are treated.
What are the key points to take away from this?
We need to be very careful about putting men on the conveyor belt from PSA testing through biopsy through to treatment. Men need to be aware that even before they have their PSA test that there are side effects which are very common with the various treatments. There are new treatments now which have fewer side effects but they still have side effects and once somebody hears that they have a cancer, it doesn’t matter whether it’s a less aggressive cancer or not, they want rid of it. So that is part of the whole decision making that men need to realise that it’s maybe not in their best interests to have their prostates removed.