Could I have prevented prostate cancer?

Why did my prostate cancer develop? Could I have done something to prevent it?

Professor Norman Maitland, University of York:

One question lots of men ask is ‘why does prostate cancer develop?’ That sort of gets translated into ‘why me?’ And my feeling is that some of it is actually just bad luck. I have a metaphor that I use, and that is that it's a bit like playing darts. If you're throwing darts at a dartboard and you stand in the normal position, your chance of hitting the bull - i.e. getting cancer - is quite low, certainly for me when I play darts. But if you have the wrong diet, or the wrong lifestyle, you take a step towards the dartboard. With prostate cancer, the problem is we don't fully understand what gives you the steps forward yet. It could be in your diet, and it's very hard to pin down dietary effects. It could be in your genes, you could be born with a predisposition to develop prostate cancer. What's at issue is what proportion of men have a predisposition, and we're not absolutely clear on that yet. Could you prevent it? Well this, I guess, is the million dollar question.

Professor Kenneth Muir, University of Manchester:

Whenever we develop a condition, be it a serious condition like prostate cancer, or even a headache, we look at our lifestyle and what we might have done that may have caused that disease. With prostate cancer, there are two issues though. The first is that maybe having a prostate cancer per se isn’t that bad. Increasingly, we're learning that many prostate cancers will not really impact on our length or quality of life. The key issue though is what leads a man to develop aggressive prostate cancer. And that's really an emerging concept, so the studies looking at that are still at an early stage. What we do know is that the environment and your lifestyle do impact on risk. But to be honest with you, we just don't know what the important elements within the environment and your lifestyle are yet, so we can't really tell you what's caused your prostate cancer.

If we're going to be serious about looking at the causes of prostate cancer, we really need to do very large scale studies, because as well as lifestyle, genetic makeup makes a difference too. But to look at the relative contributions of genetic makeup and lifestyle, we need large amounts of data, and those data sets really just don't exist. That's in sharp contrast to something like breast cancer, where there are data sets of hundreds of thousands of women. And that sort of size of data is what you need to tease out all of these different elements.

Read about a recent report from the World Cancer Research Fund about lifestyle risk factors for prostate cancer.

Should my son have a genetic test?

My mother and wife both had breast cancer. I've had prostate cancer, and my father died from the disease. What is the likelihood of my son developing the condition? He's only 21, so when should he begin to have tests for prostate cancer? Should he have genetic testing done now?

Professor Johann De Bono, Institute of Cancer Research, London and Director, London Movember Centre of Excellence:

This question is actually very relevant to a lot of our patients and the suffering they go through - not only physical pain, but also mental anguish and very often anxiety. Prostate cancer is a very common disease. Seventy per cent of men in their 70s, 60 per cent of men in their 60s and 50 per cent of men in their 50s may have some prostate cancer. So the first thing I would say is that most prostate cancers are not inherited. But a small proportion are and this is particularly a concern for patients who develop prostate cancer at an earlier age, with two or more relatives with the disease.  If there is a concern about a strong family history I would strongly recommend that they speak to their doctor and ask for a referral to a genetics expert. 

If the family history indicates that DNA sequencing would be helpful, the specialist will be able to recommend that this be done. In particular, they’ll look for some genes that we know increase risk of prostate cancer and could be inherited, for example the BRCA2 gene, and to a lesser extent, the BRCA1 gene, which are the most clearly understood. We know that mutations in these genes increase prostate cancer risk substantially. However, we don’t yet understand all inherited prostate cancer risk genes, and so it isn’t always possible to accurately predict an exact cancer risk. Having said that, it’s much easier to give an accurate risk estimate in a family with a BRCA mutation - and that wouldn’t just apply to prostate cancer, but would also be a risk for other cancers, for example breast cancer and ovarian cancer in women in that family.

Professor Tapio Visakorpi, University of Tampere, Finland:

We know that if a man has two close relatives with prostate cancer, he has about a two to threefold higher risk of developing prostate cancer himself. In this particular family, the breast cancer cases do not really have an effect. First of all, the two women with breast cancer are not genetically related. In general, we know that the genes that lead to prostate cancer and breast cancer are different genes. However, there are exceptions, one being the BRCA2 gene, which is a gene that is predisposed to breast and ovarian cancer, but also to prostate cancer. But in this family, there are only two breast cancer cases and they were not related, so it's very unlikely that either one of them carry the BRCA2 mutation.

In terms of genetic testing, that's very easy to answer. This man’s son should not be tested, because there isn’t yet a genetic test for prostate cancer predisposition. We know of about a hundred different genetic changes that we believe are associated with the risk of prostate cancer, which are currently being tested to be used in clinic. I would assume that in five to ten years from now, such tests will be available. In this case, the man’s son is 21 years old, so when he's 31 years old, he could take the test then if he wishes. And although we know that prostate cancers tend to arise earlier in men with a family background compared to those who don't, it’s still very unlikely to develop before the age of 50. So this man’s son has plenty of time to take the genetic test when he's in his 30s or 40s and it’s been fully developed.

The current recommendation is that if you have higher than average risk of getting prostate cancer, you should - if you wish - take a PSA test maybe at the age of 50. Once again, ten years from now we will know more about how to use PSA and there might actually be better markers for the detection of prostate cancers. So there is no hurry for the man’s son to take any test at the moment.

Read more about prostate cancer risk.

Why are dietary effects complicated?

Why don’t we understand the effect of diet on cause and prevention of prostate cancer?

Professor Bill Nelson, Johns Hopkins University, USA:

Most of the clues about how the diet affects cancer comes from questionnaire based research, where questionnaires are distributed that ask ‘how often per week do you eat this particular kind of food or that particular kind of food?’, and then attempts to correlate dietary patterns with the risk of getting a disease like prostate cancer.

And as you can imagine, the general sort of high saturated fat diet, in particular high saturated fats from meat, and low in fruits and vegetables, is associated with the risk of prostate cancer. However, the diet is incredibly complicated. It's the most complicated chemical mixture on the planet. And that's before you cook anything. When you cook things you change a whole variety of chemicals to other chemicals. So what are we being exposed to that's driving prostate cancer? Are there things in the diet that might be preventing it that we could supplement in some way? This has been really hard to tease out. The diet is just too complex and we need better and more complete ways to figure out how it works, and how it influences which diseases we get.

Some people wonder if there are dietary patterns that men can adopt in an empowering way to improve their health outcomes with prostate cancer. Pursuing a diet rich in fruit and vegetables and being responsible about the amount of saturated fats one consumes - the same kind of diet that can reduce cardiovascular risk for men - looks like it also helps men who have already been diagnosed with prostate cancer. We have every hunch to believe it probably reduces the chance to get prostate cancer as well.

Read about a recent report from the World Cancer Fund about lifestyle risk factors for prostate cancer.

Why does prostate cancer develop?

Why isn't more research done into why people get prostate cancer?

Professor Bill Nelson, Johns Hopkins University, USA:

There is a small amount of research into why men get prostate cancer. It's actually one of the areas I’m personally very interested in, and there are some tremendous clues. If you look in the developed part of the world, prostate cancer risks are very high, with a high level mortality. Those numbers are far lower in lesser developed countries, like in rural Asia, where men don't tend to be diagnosed with prostate cancer, and don't tend to die from it. Yet Asian immigrants to North America have been studied and their risks go up before any intermarriage. So this is not genetic. There is clearly something about the environment in North America that fosters the development of prostate cancer. Or there's something in rural Asia that reduces disease development. Or some combination of the two. I think for many years, people thought that developing prostate cancer was an essential component of maleness in some way. We know that can't possibly be true, because men who are low risk to develop prostate cancer in Asia have the same testosterone and dihydrotestosterone levels as men in North America. So that can't be the cause.

The best guess at the moment is that it's probably something to do with the diet, but exactly what has been very hard to figure out. There are lots of possible factors in the way we prepare food, which foods we eat, how we store them and how we distribute them. If we can figure it out, then presumably we could lower the chance for all men to get prostate cancer all over the world.