March 2010 podcast transcript

Welcome to the Cancer Research UK podcast. This month American scientists bring us a step closer to personalised cancer therapy, reports have over-stated the cancer risk from frying food on gas hobs, and our scientists discover a better way to deliver radiotherapy for breast cancer. I’m Simon Shears from Cancer Research UK.

00:30

An exciting new technique has been developed in America which could transform the way cancer is treated.

Researchers have developed a way to scan the DNA from a sample of a patient’s tumour, picking up genetic changes that are unique to that person’s cancer. Doctors could then use this genetic sequence to pick a personalised therapy.

The technique could also be used to monitor DNA from cancer cells that has escaped into the bloodstream, providing a readout of how well a treatment is working or whether a cancer has started growing again.

Our science blogger Henry Scowcroft described the news as important for cancer researchers because it gives them a much more sophisticated set of tools to study the disease.

“This research is very exciting. It was done by researchers in the US using a new genetic sequencing technique. It’s exciting because it raises the possibility of using this new technology on a patient-by-patient basis to develop individual tailored tests for cancer patients to allow doctors to monitor the course of their disease.

While this technique has a lot of potential, it’s still several years away. That’s partly because the technology that’s used to generate these tests is quite expensive at the moment, so the costs of doing this sort of research need to come down. But also the researchers looked at just two bowel cancer patients in their research, and it would need to be carried out on a much wider scale to confirm their findings.

Where this technique could have the biggest impact is actually in clinical trials for testing new treatments. It raises the possibility of accurately being able to measure and monitor whether a treatment is having the desired effect, and we would hope to see this making it out into a research setting in a couple of years.”

You can read more on the science behind that story on our Science Update blog, scienceblog.cancerresearchuk.org

2.18

Cancer Research UK is advising people not to worry about reports of a Norwegian study showing that frying steak on a gas hob could increase your risk of cancer.

The researchers claim that gas hobs are worse than electric hobs when it comes to creating fumes containing certain harmful particles. But there’s no evidence that these chemicals can actually harm health at the levels found in the average kitchen.

Head of health information, Ed Yong, says as long as you've got decent ventilation, the type of hob you use is unlikely to matter.

“Now we think that for people in the UK, you shouldn’t get unduly worried by this study. As long as you’ve got decent ventilation or a good extractor fan, it’s very unlikely that the chemicals given off in cooking fumes could affect your risk of cancer. We know that there have been some studies in people living in rural areas in China looking into this link between cooking fumes and cancer. While there have been some positive results, the studies have been very small, and it’s obviously a very different situation to here – people cook a lot more [in China] and they do so under poorly ventilated conditions.

So, as I said, if you’ve got decent ventilation you should be OK. Although people working in professional kitchens, chefs and cooks, need to take extra care because they’re exposed to cooking fumes much more frequently than most people are.”

And there’s more information about that story on our Science Update blog.

3.38

Finally, a Cancer Research UK trial has shown that breast cancers can be kept under control with fewer, larger doses of radiotherapy.

Researchers working on the START trial found that fewer, larger doses were just as effective as the standard treatment. This will
have a big impact on patients, as it means fewer visits to hospital.

And, importantly, women in this study said they were experiencing fewer side effects from the treatment.

Cancer Research UK’s Dr Jodie Moffat explains why the study is unique, and that there’s more to come from this trial.

“This study used a really interesting method because it actually asked women themselves about their experiences and their side effects following radiotherapy. Rather than just relying on photographs, this actually took women’s own views into account. And so while it showed that adverse effects, or side effects, following radiotherapy are actually quite common in the women, no matter how they’d received their treatment, the good news was that they tended to reduce and diminish over time.

The START trial looking at radiotherapy for early breast cancer has been a really important trial and Cancer Research UK will continue to fund it to ensure that woman are receiving the best treatment possible, with as few side effects as possible.”

4.51

Glioblastoma multiforme, or GBM, is a type of brain tumour that is diagnosed in more than 2,000 people in the UK each year. As well as being the most common type of tumour to start in the brain, it's sadly also the most aggressive.

After diagnosis, people are treated with a combination of surgery, chemotherapy and radiotherapy, but in many cases the tumour will come back. So to help improve treatment and survival, Cancer Research UK has awarded a prestigious Gordon Hamilton-Fairley Fellowship to Manchester University's Dr Gerry Thompson. He started by telling Anna Lacey about the problem with the way the tumour responds to treatment.

“So the surgeons can try and remove as much as possible, and then they can give radiotherapy to an area around that. Unfortunately the tumours are likely to come back very close to where they were in the first place. This show that even with this treatment, where you think the tumour is, there is still something going on that we don’t quite know.

Why don’t we just make the area of radiotherapy larger, to make sure it doesn’t come back around the edges? It’s a similar reason to why the surgeons can’t just go in and take out more – the brain’s obviously got a lot of very important functions, it’s a very complex thing. If you gave radiation to a much bigger area, you might damage bits of the brain that are useful for vision, for thinking or for speaking etc. And that’s one of the problems, it’s trying to give more therapy but in a safe way.

One of the things we’re looking closely at is how to give the therapies in a more targeted way. So at the moment , for example, radiotherapy is given to the area of the tumour you can see on a standard scan, plus a safety margin around it of perhaps 2-3 cm. And if there are particularly sensitive areas of the brain, then you would try to leave them out.

We want to be more focused than that – give radiotherapy to areas which might benefit from higher doses, but not give radiation to areas we don’t think will benefit. And that way you can give more conformal or tailored treatment to that particular patient at that particular point in time.”

In order to know where to give more radiation and where to give less, you need to have a really accurate picture of the tumour itself. Magnetic Resonance Imaging or MRI is the standard way of taking a safe and detailed picture of a brain.

“This is one of the standard pictures you would get. So this is someone’s head and someone’s brain. Obviously there’s the skin and the skull under it, and it you look into the brain, the darker bits here are the grey matter – you can see it’s highly folded. And this lighter area is the white matter – it’s like the wiring of the brain.

We want to use different techniques so that we can see changes that you wouldn’t normally see on these standard pictures. And there’s a lot of evidence that the bits of the GBM that you can’t see on the standard scan have already moved into bits of the white matter that look otherwise normal. So we’ve got techniques which can detect whether the white matter is behaving normally as it should. Therefore, you could say if this doesn’t look normal, it may be a problem that the GBM reached there.

The second lot of imaging techniques look at the blood flow. So when tumours arise, they make their own blood supply to keep them growing and feed themselves. And that blood supply behaves differently than the normal brain blood supply. Again, we’ve got techniques that can look at the blood supply to the tumour, and perhaps even detect the really early stage when that starts to change.”

It's all very well noticing changes, but what does that mean for treatment? Well the idea is to work out which combination of changes reliably act as warning flags for where the GBM will come back. So for example, if the white matter changes by X and the blood flow goes up by Y in one tiny area but nowhere else, then it's that tiny area that the doctor should target – focusing the treatment and thus saving the rest of the brain from damage. But to get to this stage, there's still a lot of work to do.

“We’re at the stage where we want to look at people who have GBM, see if the techniques are sensitive enough to pick up the changes, and if they do pick up the changes, would we get any benefit from that?

It’s a long way to go before this will benefit patients. But that’s why it’s so crucial that this research is done. This kind of investment will hopefully, in a few years time, lead to something that you would get as standard when you have an diagnosis of GBM. It might help with giving different, better treatments, and that would be the ultimate aim.”

That was Dr Gerry Thompson talking to Anna Lacey about his research into better ways of delivering radiotherapy for treating brain tumours.

Credits

• Presenter - Simon Shears
• Radiotherapy package - Anna Lacey
• Editor - Rachel Gonzaga
• Producer - Kat Arney
• Original music - Henry Scowcroft and Kat Arney
• With special thanks to all the contributors