We catch up with the latest in Cancer research this week, with our very own Dr Kat bringing us the news from the National Cancer Research Institute Conference in Birmingham. We find out how computers can help 'read' breast cancer scans, how to mount an immune response against tumours, and we discover the first vaccine against cervical cancer. Plus, We discover how blood cells can be used as a Trojan horse - sneaking in chemicals to improve body scans, what a 'fossil' of HIV can tell us about how disease spreads, and how beetles create their own antibiotics. And in kitchen science, Ben and Dave use the power of steam to crush cans!
In this episode
21:40 - Human Papilloma Virus
Human Papilloma Virus
with Anne Szarewski, Cancer Research UK
Helen - Cervical cancer is the second most common cancer in women under 25 and the majority of these cancers are caused by infection of members of a family of viruses known as the human papilloma virus (HPV). There are more than a hundred different types of HPV which can cause verrucas and warts and all sorts of things (genital warts) but surprisingly just two types of HPV known as strains 16 and 18 are the cause of the majority of cervical cancers. This means it's been possible to make a vaccine to prevent infection of these cancer-causing strains. This is now being rolled out across the UK and given initially to girls aged between 12 and 13. Dr Anne Szarewski is from Cancer Research UK and she joins us now to explain a bit more about the vaccine. Thanks for joining us. Can we start off first of all with just a little bit about what HPV is and why does it cause cancer?
Anne - HPV is a human papilloma virus and it's an extremely common virus. Basically it's been described as a normal consequence of having sex. It's actually so common that just about everyone's going to get it at some point in their lives. In itself it's quite boring actually but the problem is that some people don't get rid of it. Most people catch HPV a bit like a cold and months later they've got rid of it. A small percentage of people don't get rid of it and it's those people where the virus becomes persistent, where it takes hold. Then it can start to change the cells, it can make them abnormal and it can cause cancer.
Helen - And now there's this brand new vaccine which we've been hearing about i the last couple of weeks. How does that work?
Anne - Basically what it does is it mimics the virus so it's called a virus-like particle. They've taken the coat of the virus and they've made it look exactly like the coat of the actual virus. There's no HPV DNA inside so there's no active anything that could actually give you disease. It's like a ghost in a way and so what it does is it makes the immune system think that the virus is actually there. The immune system recognises this coat and it reacts to it. You get a very strong response from the immune system without there being anything present that could actually harm you.
Helen - So why doesn't the presence of the virus itself not lead to any kind of immunity and a natural way of getting rid of the cancer?
|HPV infected basal tissue © PhD Dre @ wikimedia|
Anne - It's a very interesting question and this virus appears to have evolved and adapted so it kind of sits around. What it does is it invades skin cells. If you think about this your immune system has to be more or less turned off to what goes on in your skin or we would all have loads of allergies. We'd all be atopic, eczematous. Your skin is actually relatively turned off in terms of immunity. The HPV takes advantage of that and it actually invades into skin cells which are kind of under the radar, if you like, of the immune system. It can just replicate quietly - doesn't go in the blood stream so it doesn't alert any part of the immune system that it's there. It just replicates and replicates and then skin is shed all the time. That's how it's passed on from one person to another. The other important thing to know about it is that it's not just transmitted through penetrative sex. It's transmitted though skin to skin contact so you can get it without actually having sex.
Helen - And coming back to the vaccine what sort of numbers do we need to look at in terms of protection to try and combat this as a disease in the population?
Anne - If we're looking at what's called herd immunity where you have enough people vaccinated so that the whole population becomes protected, even those who aren't, then you're really talking around 80% which is quite an ambitious target.
Helen - Absolutely. Why is it we're targeting these girls at this particular age, around 12 years old?
Anne - Two reasons. One is that the vaccines will obviously work best before there's been any contact with HPV. You want to vaccinate people before they've actually had sex. Also, importantly most vaccine actually work best when they're given to younger children and adolescents. In terms of immunity you're actually quite old by the time you're 20 which is rather a sad thought. Your immune system's already running down by then so you get the best antibody response if you actually give it to young adolescents.
Helen - Am I right that there is some level of cross-protection to other types of HPV that cause other problems like genital warts? Have we got any protection against those things as well with this vaccine?
Anne - Then I think it's important to realise there are actually two vaccines. One of them does contain the strains of HPV that would be to genital warts. The one that's been rolled out in the vaccination programme is the one that only contains the cervical cancer types. However it does appear that there is cross-protection against other HPV types but they are the cancer types. Interestingly enough this vaccine that is being used in the programme appears to have quite good protection against HPV 45 which is another of the more important ones in cancer and also HPV 31.
27:47 - Cancer Imaging - Zooming in on Cancers
Cancer Imaging - Zooming in on Cancers
with Herbie Newell, Northern Institute for Cancer Research
Kat - Joining me here in our little booth overlooking the lecture theatre at the NCRI conference is Herbie Newell and he's Professor of Cancer Therapeutics at the Northern Institute for Cancer Research. Hi Herbie.
Herbie - Hi, Kat.
Kat - We're going to talk about some very exciting new initiatives that have been announced in terms of cancer imaging. Let's take a little step back and look at what we mean when we talk about imaging. Why do we need to do it, why's it important?
Herbie - Ok, so most people are familiar with imaging in the form of x-rays or maybe MR scans and a lot of people would have had those. What we're talking about here is taking it to the next stage where you're not just looking at what's inside the body but you're looking also at the genes and the molecules inside the body. In the case of cancer the genes that have gone wrong.
Kat - This new initiative, what's all that about? What's Cancer Research UK and its partners up to?
Herbie - It's a fantastic example of partnership between Cancer Research UK, the Engineering and Physical Sciences Research Council and also supported by the Medical Research Council and the departments of Health in England. What we're doing is we're putting fifty million pounds into cancer imaging reflecting how important this is going to be to attack the cancer problem.
Kat - What sort of things are we hoping to look at? What sort of avenues are we going to be exploring with these very large sums of money?
Herbie - Well, we're going to be using lots of different techniques. First of all, as you say earlier, to try and find cancer earlier. We're expecting to have tests that will tell us when someone might have the cancer but the critical question is where is that cancer in the body? You can send the surgeons in to the right place. Then as we develop new treatments we need to demonstrate that they're working much earlier than we have to do at the moment where we do big clinical trials costing millions of pounds before we can really find out whether a drug's working. We want imaging techniques to find that out earlier.
Kat - What sort of techniques are we actually looking into? We hear about things like CT scanning, MRI scanning, PET scanning. What sort of techniques will our scientists be investigating?
Herbie - So as part of this CRUK and EPSRC initiative we're going to be using any kind of imaging that might work so for example it may be like CT where there's ionising radiation outside the body. It might like a technique called positron emission tomography where you give radioactivity to a patient. It may not involve radioactivity at all like magnetic resonance imaging. We're also looking at some optical techniques as well to try and make microscopy work but in a whole living person.
Kat - So you could actually use light to see inside someone?
Herbie - That's absolutely right. And see right down to the level of the cell, which of course is the thing we're looking for in cancer.
Kat - What sort of areas of research are the development of these techniques going to help? We talked about diagnosis earlier but are there other areas of research and cancer treatment that would benefit from this?
Herbie - Absolutely. These could play a really important part in every stage of the cancer journey. Not only catching it earlier but getting the diagnosis right. Working out for each patient what their prognosis is, how their tumour might go on, whether it's a high-risk or a low-risk tumour. Then when it comes to treatment, making sure that each patient gets the treatment that's most likely to work and also knowng much sooner whether it is working or not.
Kat - A lot of these imaging techniques are based around radioactivity so for example tracers that are put into the body. What areas are being investigated in that aspect because I think this is quite an exciting area of science?
Herbie - Absolutely so one of the big new techniques that has come on recently and the government are rolling this out across the country is a technique called positron emission tomography. It's at the other scale to electrons - they're positive electrons. You give these radioactive materials to people and they're already important for getting the diagnosis and prognosis of lung cancer right, helping with managing patients with some kind of haematological malignancy, some types of lymphoma. At the moment we've really only got one type of tracer that we use. What we'll do in this initiative is develop a whole new family of tracers that will tell us about all aspects of cancer cell biology.
Kat - For the area that you, yourself, work in: the development of new cancer drugs, cancer therapeutics - how do you think these techniques are going to help you?
Herbie - These are going to be absolutely critical because what we'll be able to do is the current experiments that we can do in cell lines in test tubes but we'll be able to do them in the only model that really matters - the patient. We'll be able to look at biochemical reactions when we put in new drugs to see whether we're affecting them in the way we want to. That will help us pick out the winners, get the drugs that are going to be the blockbusters and really help cancer patients much sooner than we do at the moment.
Kat - Sounds like exciting times ahead. In terms of the actual initiative, how's that going to work? £50 million is a bit pot of money to spend. How are you going to divvy it up?
Herbie - As ever in science we've looked at all of the centres who've worked in this area. We've looked at their proposals and decided to fund big-time 9 of the best. This is serious amounts of money that CRU, EPSRC, MRC and the Department of Health, England are putting in. With these centres of excellence we'll be able to set up a network that will get people moving together to get this exciting technology through into patients much faster.
Kat - One of the things that people get concerned about is, for example, the cost of some of these techniques. We hear that CT scanners are very expensive, MRI scanners are very expensive. I can imagine that PET scanners cost a bomb. How do you think if we do develop these techniques do you think it's going to be feasible to roll them out as widely as possible?
Herbie - It's a really important question. Our role first and foremost is to provide hard evidence that says this technique might work, this one unfortunately doesn't look so promising. Having got through that stage it then becomes a social issue that we have to recognise the value that will be brought to the individual patient and also to the whole healthcare economy by personalised medicine. That's what this initiative is all about. It's about focussing the right treatments on the right patients so we don't waste time and money with ineffective and sometimes expensive treatments being given to patients and it's not going to work.
Kat - So you can see straight away of something's not working?
Herbie - Indeed, we've got examples already where you can tell within 24 hours whether a patient is like to respond because the drug has or has not produced the effect you want in tumour cell biology. We need more of those examples.
35:24 - Wasn’t there something about shining light on skin that was a method of detecting cancers?
Wasn’t there something about shining light on skin that was a method of detecting cancers?
Chris - Yes, that's absolutely true. People have found that there's a technique that's called Raman spectroscopy. When you shine light at something the light gets bombarded or ricocheted about like bullets bouncing around a room when it passes through different substances. Depending upon the structures it's passing through you get a different fingerprint scatter pattern. We know what normal skin does. If you shine light into skin which has got a malignant melanoma on it you get a different scatter pattern entirely. Scientists are investigating this as a very sensitive diagnostic technique. You may be able to use it to pinpoint a lesion which you might think I'm not suspicious enough to want to biopsy it but I might be suspicious enough to wave one of these wands at it and it would say, yes that's got a scatter pattern that says it's got a lot of cells which are in an abnormal configuration under the skin. It could be cancer, it's worth doing a biopsy.
44:37 - Why do humans have three different blood groups?
Why do humans have three different blood groups?
Karen Humm, Emergency and Critical Care Vet, Queen Mother Hospital for Animals, London.
All animals do have different blood groups. Humans have a system based on A, B and O. Other animals have different systems. Basically the blood groups are based on little proteins that sit on the outside of red blood cells. The reason it's important for us to be able to tell what blood groups an animal or a person is in is because the blood from one person may not be compatible with another person if their blood group is not the same. In dogs we have a system called DEA 1.1, 1.2, 3, 4, 5, 6 and 7. In cats we also have A and B but they're not the same as A and B in human blood systems. We don't know exactly why people have different blood groups or why animals have different blood groups but it is very important because of the risk of interactions with different blood groups in people and other animals. It might be that some blood groups give an advantage in some circumstances and certainly some ethnic groups are more likely to have blood groups than other people. People from Mediterranean origin are much more likely to have blood group B than people from non-Mediterranean background. The actual causes of them we don't fully understand.
*And Karen also made an appeal for doggy blood donors. There is currently a UK-wide shortage of blood for canine transfusions but you can take your pet down to the vet to help out - they won't take a whole pint!
Dr John Gibson, Veterinary School, University of Cambridge
The reason for ABO groups in humans is not really known but they are of vital consideration for transfusions. They are proteins on the surface of red cells. They are inherited from parents and differ between individuals
- so you can be A or B or AB or have neither (= O). In the blood there are naturally occurring antibodies which react with the blood group proteins which you don;t have. So if you are group A, you will have antibodies against group B. The antibodies will react if they see red cells with the group that they target. So a group A person needs to avoid transfusions from a group B person. As well as ABO groups, there are lots of other blood groups like Rhesus and Duffy. To most of these, there are not naturally occurring antibodies, so they are less important for a single transfusion - but the antibodies can be made following a transfusion.
But the reason for these groups is not really known. There is some association with diseases but it is weak for ABO and no real function for the proteins is known. Some other groups are proteins which do do things like act as membrane transport systems or dockage points for parasites.
Animals do not have the human ABO group on their red cells. But they do have other blood group proteins which are sometimes similarly important for transfusion. Dogs have DEAs (dog erythrocyte antigens), about 8 important ones of which DEA4 and 6 are most significant for transfusions. Cats have groups A, B or AB (but they are not quite like human ABO). Horses have groups including A, C, D, K, P, Q and U. Sheep A, B, C, D, M, R and X. Goats A, B, C, M and J. And so on. Whether these are important for transfusions depends on whether naturally occurring antibodies are present. As for human, its worth testing whether an animal's plasma has antibodies against a potential donor animal's blood.
Are there treatments for womb cancer?
Chris - Yes, there are. This is endometrial cancer. It's not that common but common enough that it's a major problem. Obviously it only affects women because men don't have a uterus. the common associations are it tends to be in people who've been exposed to certain hormones in life. It's also linked ot certain types of breast cancer, it's genetic and it's also linked to people that are carrying a bit too much weight. All those things are risk factors for endometrial cancer. The sign that it might be going to happen is people develop bleeding when they shouldn't be bleeding. In other words, when they're post-menopausal or inter-menstrually so that's a sign there might be something wrong. In terms of dealing with it there are a number of approaches. One of them is surgery. If you remove the organ then that takes the cancer out of the body. The other way to do it is sometimes used in addition to subsequent surgical treatment which is that you can use radiation. You can put these pods, if you like, into the vagina and they contain a radioactive source which is put up close to where the uterus is. The radiation comes out, goes into the cancerous cells and damages them. Then you can kill the cancer that way. Then you withdraw the whole apparatus and this is a way of preventing it. There's a number of different treatments and there's also people investigating various hormonal treatments as well. I don't know of any clinical trials that are doing that at the moment.
Is there some way of detecting cancers using sound waves?
Chris - Definitely. This was experimental but very exciting. One of the big problems with cancer spreading around the body or cancers that may be so tiny or almost impossible to see on the skin surface, for example, is how do you know if they're already in the blood stream? Cancers throw off cells. These are called metastaces or metastatic cells. If you've got malignant melanoma which is making a lot of melanin, a dark pigment what you can do is take blood samples and there might be one in a million cells in the blood stream which is a malignant melanoma. Scientists have found that if you zap this with laser light at a frequency which the melanoma will absorb but other cells won't then the cell can be made to resonate. It makes a sort of snapping or ricocheting-like noise which you can hear with a very sensitive microphone and this tells you the cells are there.
How do plants protect themselves from UV damage?
Chris - There was a study that was done on edelweiss, not just the song in the Sound of Music. This is a plant that grows high up in the alps. Because it's growing at altitude it's exposed to a lot of solar radiation and a lot of ultraviolet so how does this fend off? Scientists recently published a paper in which they looked at the surface of the leaves of edelweiss and they found these tine hairs. If you zoom in on the hairs the hairs are made of even tinier filaments which are about 100nm across. 100nm is roughly the wavelength of ultraviolet light. These hairs interfere with or interrupt the passage of the ultraviolet light, stopping it getting onto the leaf surface. Instead they channel the ultraviolet into some water in the middle of the hair and this soaks up the UV and protects that plant. Helen - Could we make this into anything we could use? The new generation of sun creams perhaps?
Chris - That's not such a silly thing to say because yes, people are saying we might be able to make nano technology sun cream. Sun cream uses titanium dioxide that you just spread on the skin. They're saying if we made edelweiss extract you could rub this on the skin and the same trick might work to fend of the UV rays.