Chris Hoy's cancer diagnosis, and AI finds us common ground
In this edition of The Naked Scientists: Sir Chris Hoy goes public with his terminal prostate cancer diagnosis; the World Health Organization has declared Egypt malaria-free; also, it's time to change the clocks in some countries. But what impact does it have on our perception of time?
In this episode
00:56 - Chris Hoy announces terminal prostate cancer diagnosis
Chris Hoy announces terminal prostate cancer diagnosis
Vincent Gnanapragasam, University of Cambridge
Sir Chris Hoy, the six-time Olympic cycling champion, has said he has been "blown away" by the number of men seeking cancer advice since he revealed his terminal cancer diagnosis. Sir Chris - who is 48 - has said that a primary cancer in his prostate has also spread to his bones, and that he has between two and four years to live. To find out more about prostate cancer, I went to meet Vincent Gnanapragasam, who is professor of urology at the University of Cambridge and a consultant at Addenbrooke's Hospital…
Vincent - It is extremely common as we get older. And prostate cancer is really a disease of the ageing male. The incidences and the chance of finding it is much higher the older men get. But there are no symptoms with prostate cancer unless it is extremely advanced or has spread. And urinary symptoms in particular are really not a sign of prostate cancer at all.
Chris - So when people complain of getting up in the night to go for a wee, for example, this is not a sign of prostate cancer. It's a sign of something happening in the prostate, but not cancer per se.
Vincent - Absolutely correct. So the prostate enlarges with age and there's other mechanisms which actually change as we get older that does cause those symptoms, but it is not prostate cancer unless it's extremely advanced, which is a fairly rare presentation, particularly for urinary symptoms. In fact, many studies have shown there's an inverse or opposite correlation between having urinary symptoms and the chance of finding prostate cancer. But of course, because men go to GPs because of the urinary symptoms, they may be found to have prostate cancer by chance. So that association has stuck in the mind of the general public, and in fact many doctors.
Chris - Given what you've just said about age being the biggest risk factor, Chris Hoy is therefore presumably very unusual to be just in his late forties and having this.
Vincent - You are right, the chance of finding prostate cancer in a man under 50 is about 1 in 500. The chance of having such a lethal or aggressive cancer, as has been reported in the media, is much, much less than that. In fact, if you look at the national statistics in the UK, actually prostate cancer only contributes about 3.8% of all male deaths. And that is across the ages of 30 to over 90. In men in Chris Hoy's age group, you're talking about less than 0.01%. And even among men in their eighties, it's about 4-4.5%. So overall, prostate cancer actually is not a major cause of male deaths in the UK or worldwide, but of course it's very common. And the complexity of prostate cancer is how to manage it so you don't overtreat things, but equally find those aggressive cancers early enough to be able to actually do something so that it doesn't cause death.
Chris - Well, let's look at the first of those things first, which is how we manage the disease. Say someone like Chris Hoy presents with prostate cancer, how is that controlled or managed or investigated?
Vincent - Prostate cancer is complex because it can have a very indolent path, as I mentioned, or an aggressive path. And actually most prostate cancers will never go on to cause death or mortality in a man. So a lot depends on getting that characterisation of disease first, and also for the doctor or the nurse seeing this patient to actually understand what are the many factors that have to be considered before you decide on treatment or in fact keep an eye on things, which is actually becoming one of the most common ways of managing prostate cancer. Now, in the case of Chris Hoy, that's a very different spectrum. As I understand it, he's been diagnosed with cancer that's already spread, and as I've mentioned, that's extremely rare. In fact, I don't think I've ever seen anyone of that age present with metastatic or cancer that spread. Now, once that happens, it is incurable. But these days there are many, many lines of, uh, treatment and things which can help to prolong life. But like I said, again, it's important that we don't overemphasise that lethal side because it is a vanishingly small part of diagnosis in a young man.
Chris - And what sorts of treatment options are there?
Vincent - Diverse. And they range from surveillance or monitoring, which is where you keep an eye on things because you know the risk from that cancer is low and a man is more than likely going to die of something else. And again, it depends on presentation because right at the other end of the scale, if you have someone who's got cancer that has spread, then you're talking about different lines of drug therapy, particularly blocking the male hormone, perhaps some radiotherapy as well. And then further down the line, perhaps chemotherapy, and then more experimental things such as a new wave of agents which are targeting mechanisms in the DNA which have changed, which are found in a proportion of these men.
Chris - In terms of picking it up, because that was the other point you highlighted, what options are available to us there?
Vincent - If you're looking for or trying to detect prostate cancer early, the primary way to do that is by the serum PSA or the blood test, the PSA test. And there are many efforts trying to do that, including looking at genetic risk scores or other markers. But all of these things, including PSA, have a big problem in that they don't pick up the lethal cancers preferentially. They do, but they'll pick up lots of cancers and a lot of those cancers will not cause problems. So the problem in prostate cancer is not so much that we haven't got tests that will pick things up. But the problem is when we do, what do we do about it? If we accept it that a raised PSA test, for example, could lead to a diagnosis, but that diagnosis doesn't necessarily mean you need to be treated, then actually that's a very practical and pragmatic way to manage prostate cancer. And that's what we do currently in the UK, which I think personally has the best rationale for how to manage prostate cancer. But it doesn't take away from the fact that there are specific high risk groups where finding things earlier may be better. And that's really the most novel modern concept is how to identify those higher risk groups.
Chris - And who are those people? Who's in the high risk category?
Vincent - So specifically I would say men with a strong family history, and the key word is strong family history. So just because you've had a father who's had prostate cancer in his seventies or eighties, that doesn't make it a strong family history. We are really talking about men who in the male lineage in particular have got fathers, brothers in particular diagnosed at a young age with aggressive disease. In some families where you have what's known as the BRCA mutation, which also can lead to breast cancer, finding that in familiar lines will put you at higher risk of developing cancer. But the complexity here is it doesn't always mean it's going to be aggressive cancer, but you should start to look earlier. Black men have a higher risk of also finding cancer. And so those are a higher risk group as well. And there are some other smaller groups of family members who actually carry mutations, which would be considered high risk.
07:56 - Egypt declared malaria-free
Egypt declared malaria-free
Jane Carlton, Johns Hopkins Bloomberg School of Public Health
The World Health Organisation has certified Egypt as malaria-free. It marks a significant milestone for Africa’s third most populous nation, which is home to more than 100 million people. I've been speaking about the implications with Jane Carlton who is the director of the Malaria Research Institute at the Johns Hopkins Bloomberg School of Public Health…
Jane - It's actually one of the big three infectious diseases, which includes HIV/AIDS and TB. And malaria itself is really a tropical disease, so it's found in parts of South America, Southeast Asia, but in particular in countries in Sub-Saharan Africa. And there it causes about 600,000 deaths each year and about 250 million cases each year. So it's really a significant global public health burden.
Chris - And how long has Egypt been struggling with it?
Jane - Actually, for hundreds and hundreds of years, it's been known that Egypt has struggled with malaria because there have been studies looking and identifying the malaria parasite DNA in mummies from ancient Egyptian times. And so we know that, for example, some of the famous pharaohs died of malaria. And in fact, in the 1940s malaria cases in Egypt really surged to over 3 million per year. And this was mainly due to population displacement during World War II and also due to the construction of the Aswan Dam, which was in the 1960s. So it's been a significant burden in that country for many, many years.
Chris - And what manoeuvres or measures have Egypt gone through in order to try to bear down on it? And why is this now finally succeeded?
Jane - The sorts of measures that countries use to try and decrease the malaria burden are pretty common from country to country. It will include trying to drain some of the swampy areas of the country, and those are the prime mosquito breeding grounds. So mosquitoes transmit the malaria parasite. It's actually the malaria parasite that gives you malaria, not mosquitoes, but in order to stop what they call the transmission chain, what you want to do is to try and decrease the number of mosquitoes or stop mosquitoes from biting people. So if you can stop them from breeding through, getting rid of many bodies of standing water, which is where they like to breed, that's one step in the right direction.
Chris - And the box that's been ticked here is that they have eliminated malaria transmission in Egypt. This is a temporary thing though, presumably. It could come back if any of those pressures or any of those measures are allowed to lapse and the mosquitoes regain a toehold, the disease gets back into the population, presumably we're back to square one.
Jane - It is a bit like that unfortunately. In order to be certified malaria free by the World Health Organization, which is a United Nations institution, a country has to be malaria free for three consecutive years. And that basically means that there can't have been any malaria cases that were transmitted through mosquito-borne bites in that country. So Egypt has already been under scrutiny to make sure it can maintain this for the past three years and going forward, as actually has been mentioned by the World Health Organization, they will continue to need to be vigilant and on the lookout for any increases. And that's because mosquitoes don't know borders. Mosquitoes can fly from one country to the next. And so if the surrounding countries roundabout Egypt have malaria too, then of course that can be brought into Egypt. So there will continue to be what we call surveillance measures, both for the mosquitoes and also for infected people in Egypt to really try and keep the lid on the disease resurging.
Chris - Are we at risk of, or is Egypt at risk of, jumping out of the frying pan and into the fire? Having got rid of malaria, could there not be other diseases hot on its heels that do quite like the urban environment, the high population density that countries like Egypt, as Africa's third most populous nation, and also Cairo, very heavily densely populated, could end up with other diseases? I'm thinking things like dengue spread by different kinds of mosquitoes that really flourish in urban settings.
Jane - That's very true, but it's not that if you get rid of malaria, something else will pop up in its stead. Dengue, a different species of mosquito, not the same one that transmits malaria parasites, it's not going to sort of jump into the niche as we call it, of malaria. The good news is that the methods that we try and use to decrease the mosquito population, and some of those can be quite sophisticated actually. From things like stopping the mosquitoes from breeding, through inserting a gene into its genome, through other basic types of methods such as spraying areas with insecticide. Those sorts of measures won't only decrease the mosquito population that transmits the malaria parasite, but also those mosquitoes that transmit dengue too. So in fact, it's good news all round, I think for other diseases which are transmitted by so-called vector-borne diseases.
Chris - And is it good news for other African countries that haven't yet achieved what Egypt has, but can they take their lead from what they're doing and try to emulate it?
Jane - Yes, it is, of course, very good news. I should say though, that these methods are used by many countries. Sometimes it's just a numbers game and a time game as well. And then how many resources are available in order to be able to roll out these methods of control as we call them. But certainly, yes, I think every time a country is certified as malaria free, there's a sort of sigh of relief among all of the other malaria countries because we're really starting to make an impact on the burden. And so a total of, I think, 44 countries have now been granted malaria-free status. But in fact, that leaves another 85 or so countries that still have a big malaria problem. So it's those countries that we'll really be focusing on in the next few decades.
15:11 - AI can help us find common ground
AI can help us find common ground
Christopher Summerfield, University of Oxford
A new study has found that an artificial intelligence tool can help people with different views find common ground. It works by more effectively summarising the collective opinion of the group than humans can. The work was carried out by Google DeepMind and the findings have just been published in the journal Science. Christopher Summerfield at the University of Oxford was involved in the research and he’s been telling me all about it…
Chris Summerfield - The idea behind the project came from a concept which is well known in political science, that our democratic processes can be facilitated if you sample representative groups of people from across the country and get them to, and get them to thrash out their point of view on a political issue. We wondered whether artificial intelligence could be used to make that process simpler. If you have a group of people who want to decide something and you get them around the table, the first limitation is that a table is only so big and so you can only fit so many people around the table. And the second limitation is that when you're having a discussion face-to-face, only one person can talk at a time. And we wondered whether you could overcome those limitations by getting an AI to listen to all the different viewpoints and to generate an output which summarised their collective opinion.
Chris Smith - How do you actually train it to do that in the first place, Chris? Because, for instance, if I wanted to do the equivalent thing medically, I wanted to ask an AI engine, has this person got cancer by looking at a brain scan or something? I'd have to have trained it on what a normal brain looks like so it can spot an abnormal one. So how can you ask it to synthesise a collective opinion when all it's got is a snapshot of a few people's perspectives at that meeting?
Chris Summerfield - Great question. So we did in fact train it. We got together small groups of people and we got them to write their private opinions about issues that related to UK public policy. So things like, should we lower the voting age to 16? And we got the machine to generate an opinion, which you can do because language models, you can ask them things and they will respond. And we then got people to rate whether they agreed or disagreed with the thing that the language model said. By doing that over and over again with lots and lots of participants, we were able to train the model to make a really good guess about whether people would be willing to endorse a statement which was generated by the model.
Chris Smith - If you've got a model which is trying to take everybody's viewpoints into account, don't you just end up with it smearing into the middle and everyone's kind of vaguely happy, but no one's unhappy, but no one's delighted either.
Chris Summerfield - I think that's a super question and there's nothing in the model which will give more weight to one of the participants in the discussion than any other. It's very explicitly trained to give equal weight to everyone who participates. The selection is really beyond the control of the machine itself. But once you have a group which is composed of a bunch of people with different views, what the model more or less, not quite guarantees, but what we trained it to try and do is to produce the opinion which is going to kind of form the best representation of the distribution of views that you get in that group. And so what that means is rather than just, for example, finding compromise is it seems to learn to write a statement which reflects obviously the majority view, because in a democratic process the majority should be a guide for what the solution is, but it also really strongly represents the minority view. So it gives the people reading the statements, we think, the sense that even if their view was in the minority, that their voices feel heard.
Chris Smith - Did you try poisoning the well as it were just to see what would happen if you injected some really extreme viewpoints in there and see if they were captured nevertheless. Or synthesise some responses that were so way off the normal distribution of normality. Did it end up chucking those in and did you get any bizarre hallucinations out of this? Because that's been the other thing that people have worried about with AI systems, isn't it? It just sort of confabulate things and we end up with things appearing that we don't really think are grounded.
Chris Summerfield - So we did do those kinds of tests, although we didn't do them with sort of politically toxic inputs. Rather we made sort of silly messages which had nothing to do with the question at hand. And what we found was that to a great extent, the model was prone to ignore contributions to the debate, which were completely irrelevant to the argument. Because it's been trained to be clear and concise, it knows to basically ignore that information. As for factuality, we didn't control the factuality of the responses. And that would be a very interesting innovation because when citizens juries happen, one thing that the mediators do is they sort of fact check, rather like the moderator did in the recent debate between Trump and Harris.
Chris Smith - How do you see this being deployed then? Do you think that this is effectively something that could be used as an adjunct to the current process? Or could we go the whole hog and just say, right, we are going to have a citizen's jury and we're going to feed all the perspectives en masse into a system like this and what comes out? That's what we're going to go with.
Chris Summerfield - The computer-mediated process that we've built is never going to replace face-to-face deliberation. Face-to-face deliberation obviously has many, many benefits which our tool would never be able to recreate. Such as, when you discuss with someone, you very often build up feelings of kind of empathy or mutual understanding that have nothing to do with the specific outcome of the statement that you end up generating. But what we can do is we can run deliberation at scale at a very commercial end of the spectrum. You could use it for things like market research, but perhaps the most interesting application is in thinking about the political process itself, the ability to aggregate or combine the views of lots and lots of people provides an opportunity for us to surface information to political leaders about what everyone thinks about everything else. And that, I think, could be extremely valuable.
22:09 - Clock changes alter our perception of time
Clock changes alter our perception of time
Ruth Ogden, Liverpool John Moores University
It’s that time of the year when the clocks go back. The plan is that with the arrival of winter in the Northern hemisphere, we unnaturally shift time to allow us to have more sunlight in the morning. But it can also play havoc with the way we function, and may even distort our perception of time, at least for a while. This is what Ruth Ogden, a professor of the psychology of time at Liverpool John Moores University, is trying to find out…
Ruth - We did some research during the pandemic, which showed that people en masse experience time differently, particularly during lockdowns. So the research we did in the UK showed that about 80% of people experienced time differently during the pandemic in comparison with before the pandemic. And of that 80%, about half felt like time was going more quickly and half felt like time was going more slowly. Basically, people who were coping well felt like time was passing quickly. So they had a short, fast pandemic. but people who were struggling felt like they had a long slow pandemic. So what we're trying to understand is, how do these changes in time affect our ability to cope and our ability to recover from trauma, both during critical life events but also afterwards. So do you feel like your life gets back to normal? Do you feel like your time gets back to normal or do you constantly feel slightly discombobulated like you are not quite in sync with everyone else? And if you're not quite in sync, what does this do to your sense of wellbeing?
Chris - What do we understand though about how our brain registers the passage of time? Because I can remember, distinctly remember, when I was a little kid and my parents used to take me to see my grandparents, they lived a reasonable distance away so it was quite a long car journey for a three or 4-year-old. The journey there seemed to take forever, but coming home went more quickly and I noticed that even from a young age. So why would I have had that experience?
Ruth - One of the ways in which we keep track of time is by paying attention to it. If you pay too much attention to time, time drags. If you pay too little attention to time, time flies. So in the example of a car journey, you are thinking about when you're going to be there. There's a high degree of uncertainty about when you're going to arrive. So you pay lots and lots of attention to time. Are we nearly there yet? And that makes that time drag by. The other thing that makes time drag by is when we are experiencing lots and lots of new things. We formed lots and lots of newer memories. And when we make lots of new memories, when we look back on that period, we assume that it was a long period of time. So you're going on a car journey, you don't know where you're going. You're seeing lots of new things that help to make that journey feel really long. When you're on your journey coming home, it's familiar. You know where you're going. There's much less uncertainty.
Chris - That presumably is why people talk about time slowing down when something catastrophic happens. They witness an accident or they're in a horrible situation and they reflect on it afterwards and think, ‘well, time almost appeared to slow right down. And I could see a series of snapshots of that enriched memory.’
Ruth - The way in which our brain processes time is heavily influenced by emotion. What we see in our studies is that when we experience a very high level of emotion, so our hearts beat really quickly, we are sweating, we feel like we might die, the activity of that area of the brain is increased and that distorts our sense of time. So one idea is that it provides us with some sort of advantage. If you are about to die and you see things in slow motion, then maybe you've got more opportunity to think about your responses. You've got more opportunity to plan your responses. You're seeing everything that little bit more clearly and that provides you with this advantage to survival. So we think that that's how this is developed throughout our evolutionary history.
Chris - That's extremes, and also longer term experiences of the passage of time. Something that's going to happen this weekend is we are gonna change our clocks. And you've written a piece this week where you're quite interested in how that affects people's perception of time. Why are you interested in that specifically?
Ruth - Every year, twice a year, people in the UK experience an imposition of time. So we switch the clocks forward and we switch the clocks back. And this changes our rhythm. We're incredibly rhythmic creatures. We like to do things at roughly the same time, on roughly the same days. And this helps to keep us in order within our lives. It helps us to feel like we're in the right place at the right time. When we change the clocks, all our normal temporal cues, they all go, they suddenly become out of sync. And we know that this change of the clocks has a really significant impact on health. So heart attacks increase in the days after the clock changes. Road traffic accidents can increase as well. But what we don't know at the moment is how it feels to have the clocks change. We have a really poor understanding of the impact of this on our psychological health and the way in which we experience time in day-to-day life. So what we are trying to do in our study is to understand what are the implications for people's lived experience of time and their lived experience of wellness after a change in the clocks. And we're hoping to use this information to help us to determine, well, is this something that we still should be doing? Or do the costs outweigh the benefits?
Chris - Where do you sit on that? Because when we looked into this on a previous program, there seems to be arguments in favour of both not changing clocks, but also changing the clocks. And it wasn't easy to say there's a black and white situation here. It's not day and night, excuse the pun.
Ruth - <laugh>. So I can only agree with what you've just said. Part of the reason that we're doing this study is that we don't know what the costs and benefits are in enough detail to make an informed choice about what should be done on a population level. What I would say is that in all situations, there are always what I would call temporal winners. So people who experience an advantage in time, because of a change. And temporal losers, so people who perhaps feel like they've got less time or they're more time pressured, find it more difficult to get out of bed in the morning, feel more depressed as a result. And I think the question that we need to be asking ourselves as a society is, well, who are the winners as a result of this change? And who are the losers? And how can we better equalise or better improve the experience of the people who are struggling the most with this change? What systems or resources can we put in place?
Chris - So tell me, Ruth, did this interview go fast or did it go slowly?
Ruth - It absolutely flew by because I was enjoying myself.
28:56 - Do other planets have the same chemical isotopes?
Do other planets have the same chemical isotopes?
Thanks to Xander Byrne for the answer!
James - Elements from the periodic table are ordered and defined by the number of protons in each of their atoms. This is the atomic number. For Carbon, that’s 6. But some atoms vary in the number of neutrons bound up with the protons in their nuclei. These variants are called isotopes, and while isotopes of the same element will share the same atomic number, they have different atomic masses. As you rightly identify, Pamela, carbon 12 (6 protons, 6 neutrons) and the rarer carbon 13 (6 protons, 7 neutrons) are the stable isotopes here on Earth, meaning that the nuclear force binding together the atoms is strong and so they stick around. But why are they distributed in that 99:1 ratio and, to your question Pamela, what about on other planets? Do we see a similar abundance of these isotopes? Here’s Xander Byrne from the University of Cambridge’s Institute of Astronomy…
Xander - The short answer is yes! Carbon is made in stars by nuclear fusion, and nuclear fusion has this quirk where odd-numbered isotopes like carbon-13 are generally a lot harder to make than even-numbered isotopes like carbon-12. And because the laws of nuclear physics seem to be the same everywhere in the Universe, you'll always have a lot more carbon-12 than -13. If you give me a lump of coal and ask me to take out all of the carbon-13, it's actually very difficult, because chemically, different isotopes behave almost identically, because fundamentally they're still the same element. They faced a very similar problem in the Manhattan project, because to build a nuclear bomb, you can't just use any old uranium, you need uranium-235, but 99% of naturally-occurring uranium is 238, so they had to come up with all sorts of clever ways of "enriching" it, to get the isotope that they wanted.
James - Remember. the only difference between isotopes is their mass: carbon-13 is a little bit heavier than carbon-12, and this slight difference has big consequences…
Xander - That’s right. It makes carbon 13 VERY slightly lazier - meaning it doesn't react as often. So when plants photosynthesise, taking CO2 out of the atmosphere, they preferentially take in molecules with carbon-12, and as a result, living things have even less carbon-13 than is in the atmosphere. In 2022, the Curiosity rover analysed some of the rocks in a crater on Mars, and found barely any carbon-13, which got people wondering: could this be a signature of life on Mars? But life isn't the only thing which can cause this isotope fractionation; another possibility is that it's just the way UV light from the Sun interacts with the CO2 in the atmosphere, and that would also account for this signature. What's really exciting is that we're finally able to look at isotope ratios in planets outside our Solar System. There was a study last year looking at a planet called VHS 1256b,
and because different isotopes absorb slightly different colours of light, by looking at the planet we can measure how much of each isotope there is. They found that rather than being only 1% carbon-13, this planet had about 1.5%. Now that might not sound like a huge difference, but that actually tells us a lot about the different processes that were going on when this planet was forming, and the fact that the isotope ratio is slightly different from the Earth suggests that other planets might form in very different ways than we did.
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