Science Interviews

Interview

Sun, 2nd Oct 2005

Diagnosing Skin Cancer With Light

Symon Cotton, Astron Clinica, Cambridge

Part of the show Science of Lasers, Light, Kung Fu and Archimedes

Symon - We make and sell a piece of equipment that helps to diagnose skin cancer and other skin diseases. And it does this by helping to unobtrusively probe beneath the skin. It's better than existing technologies because it gives more information to doctors. More information means that they can make better decisions.

Chris - How can we use light to diagnose skin problems?

Symon - the skin is nice and easy to get at because it's on the outside of the body. This makes it a very good thing to look at with light. The research we've been doing is to look at how different types of light interact with cells. After we've seen that, we can start to measure things about the cells, such as how many there are and their pattern over the skin. Particularly with types of skin cancer, we can identify certain types of cell and work out where they are. For instance, in melanoma, certain cells called melanocytes should be in a certain layer of the skin. If they become cancerous, they can start to grow in the second layer of the skin, and that's the key bit of information that dermatologists would like to know, and in particular the pattern they form. They can use this information to diagnose this kind of disease. They have to make the decision whether to have the lesion removed.

Chris - Presumably shining a light on the skin is much quicker than a pathologist having to remove it and have a look under the microscope. How good is using light compared to the pathologist?

Symon - Well the pathologist looking down the microscope is still the gold standard for doing the diagnosis, but if the pathologist never gets to see the bit of tissue, it doesn't matter how good they are. People are faced with the very difficult decision about whether something should go to the pathologist or not. Currently, diagnosis rates are at about 80%, so about 20% of these are being missed or coming through later.

Chris - So people have had skin cancers and it's been overlooked?

Symon - It is sometimes overlooked, and often picked up at a later date when it's harder to treat. The whole emphasis with skin cancer is diagnosing early. If you can give more information on how skin cancers grow, if they're picked up early enough, the following treatment is much less aggressive.

Chris - So how does your piece of equipment actually work?

Symon - We use light to identify different types of cells. We can do that because different types of cells absorb light in different ways. Some of them will absorb different colours more than others. But the other thing we critically use is that when these cells move into different parts of the body, the light moves indifferent ways. In the top layers of the skin, there is very little scattering, so the light doesn't bounce around very much. But in lower layers of the skin, it's a highly scattering area. Because of the way light bounces around, the colour that the cells appear changes, and we use that to identify the type of cell and critically, where it is.

Chris - I think it's important to say that this is something that we should be worried about right now. I think the cited figure is that there has been a 100% increase in melanoma rates in the past ten years.

Symon - We should be very concerned about melanoma. Melanoma is a ver very dangerous disease, but if it's identified early, then the treatment can simply be to have the lesion removed. However, the point is to get that lesion identified and removed early. If it's removed early, the treatment is very effective. If it's removed late, then the treatment has to be very aggressive. The whole emphasis is early diagnosis. If you have a funny looking mole that's changing and itching, then go and see your doctor because early diagnosis is the key.

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