For Cancer-Detecting Canines, The Nose Knows

Transcript

RACHEL MARTIN, HOST:

A new clinical trial is set to begin in the U.K. using dogs to detect prostate cancer. While research has been done before, this is the first time Britain's National Health Service has gotten on board with this. The trials at the Milton Keynes University Hospital are happening with help from a charity called Medical Detection Dogs. Dr. Claire Guest is a behavioral psychologist, and she co-founded this organization back in 2008. She joins me now. Thanks so much for being with us.

CLAIRE GUEST: Hi.

MARTIN: First off, can you just explain how this happens? How do dogs detect prostate cancer or any kind of cancer for that matter?

GUEST: (Laughter) Well, dogs, as we know, have got this fantastic sense of smell. They've got 300 million sense receptors in their nose. Us humans have got a - sort of poor five million. So they are fantastic at smelling odors at very, very low levels. And what we've now discovered is that lots of diseases and conditions, and cancer included, that they actually have different volatile organic compounds, these smelly compounds, that are associated with them. And dogs can smell them.

MARTIN: So may I ask how this actually happens, practically speaking?

GUEST: Indeed, so during research phase, obviously what you're doing is you're training dogs to detect the odor, and then you're testing them to see how reliably they can find it in unknown samples. The samples come to the dogs. The dogs never go to the patient. At the moment, our dogs would be screening about between a 0.5 and a 1 ml drop of urine. They come to the dogs at our training facility. They're put into a carousel, and the dogs go around smelling samples. If they come across a sample that has the cancer smell, they'll stop and stare at the sample and wait. They won't move on.

MARTIN: What's the benefit of having a dog do this? I mean, is this more reliable than getting a CAT scan?

GUEST: Well, indeed. I mean, the challenges are, of course, in cancer diagnosis, that some cancers - ways of diagnosing cancer can be very, very expensive. So, for example, prostate cancer, we have a situation where we have a blood test, the PSA. It does reliably indicate if cancer's there. It's a low false-negative but a very high false-positive, meaning that 3 out of 4 men that have a raised PSA haven't got cancer. So the clinician then has a very difficult decision to make. Which of the four men does he biopsy? What we want to do is provide an additional test, not a test that's stand-alone, but an additional test that runs alongside the current testing which the clinician can use as part of that patient's picture, in terms of results. And then he can make a decision whether a biopsy is necessary or not.

MARTIN: I understand you had breast cancer yourself, and one of your dogs helped you realize that. Is that true?

GUEST: Indeed, yes. I mean, I'd been training cancer dogs since 2002, and I had a dog who's a very - and still is - our most reliable prostate cancer detector dog. She was working on a project with me. But she started, for a short time, to be a little bit anxious around me and one day kept jumping and staring at me and nudging into my chest. I found a lump which I hadn't been aware of. I sought, you know, medical advice and actually that particular lump was fine. But I had a very, very deep-seated breast cancer. I had surgery and treatment, and I'm glad to say I'm fully recovered. But it happened at a time when there was a huge amount of skepticism about whether dogs could in fact add anything to the future of the diagnosis of cancer. It kept me focused on the fact that I knew that dogs could offer something. If we can diagnose cancer reliably by screening non-invasively, screening for volatiles, then of course this could save thousands of lives in the future.

MARTIN: Dr. Claire Guest is the co-founder of Medical Detection Dogs. Thanks so much for talking with us.

GUEST: Thank you very much. Transcript provided by NPR, Copyright NPR.