Can dogs detect the smell of cancer? Cancer Research UK looked at this question, one that has surfaced a lot since the broadcast of a BBC documentary in 2006.
It’s a well-known fact that dogs have a much better sense of smell than humans. Dogs are routinely used to sniff out drugs, bombs and people. Smells come from molecules diffusing in the air detected by the scent receptors. Tumours – such as lung cancer, or breast cancer – give off unusual volatile molecules, which could account for stories where dogs have sniffed persistently at the area on their owner’s body.
Several small studies have been carried out in recent years. Scientist Carolyn Willis worked with her colleagues to train dogs to tell the difference between urine samples from patients with bladder cancer and people without.
The dogs picked out the urine samples from those who had cancer 41 percent of the time.
In another study, Michael McCulloch and his team trained five dogs to distinguish between breath samples from lung and breast cancer patients. Within a few weeks of training, the dogs could correctly spot the samples from cancer patients.
However, in yet another study, Robert Gordon and his colleagues found that of their six dogs only two were better at detecting urine samples from breast cancer patients. The three studies were all very small studies, and Cancer Research UK’s scientific information manager, Dr Kat Arney, said any test for cancer must be “reliable, specific and practical”.
The charity Medical Detection Dogs is currently carrying out an NHS ethically approved study into dogs’ ability to detect urological and breast cancers by smell. The charity says: “The UK has one of the worst cancer survival rates in Europe – because of late diagnosis. At Medical Detection Dogs, we believe our research will help early diagnosis improve in the future.” The Medical Detection Dogs’ research will look at prostate cancer, among others, and Dr Arney said it would be interesting to see if this new trial shows that dogs can identify prostate cancer better than current tests. In the UK, one man dies from prostate cancer every hour.
Because dogs are able to detect tiny odour concentrations, around one part per trillion (the equivalent of one teaspoon of sugar in two Olympic sized swimming pools), they are potentially able to detect diseases, such as cancer, much earlier than is currently possible. Their pioneering work could help to speed up the diagnosis process and impact on thousands of lives. Dogs are currently trained to detect urological cancers and breast cancer, as well as other diseases. If you want more dogs like this, you can donate to Medical Detection Dogs here.