I can just see the scene now: You’re sitting in the reception of a clean and modern doctors surgery. “Dr Rover will see you now” says the young receptionist. You walk through the door into a small empty room that smells of wet dog. You stare bewildered at the small Yorkshire terrier sitting on the floor in the corner with a stethoscope round it’s neck…
Dogs do as well as state-of-the-art screening tests at sniffing out people with lung or breast cancer. The research raises the possibility that trained dogs could detect cancers even earlier and might some day supplement or even replace mammograms and CT scans in the laboratory.
Two previous studies have shown that dogs seem to be able to sniff out melanomas and bladder cancer. The idea is not outrageous. Cancer patients have been shown to have traces of chemicals â€“ like alkanes and benzene derivatives â€“ in their breath, and other studies have shown dogs can detect chemicals in concentrations as small as a few parts per trillion.
To test how well the dogs had learned, they used a new batch of samples and had the dogs attempt to distinguish among 55 lung cancer patients, 31 breast cancer patients and 83 healthy controls. The patients had all had their cancers confirmed by biopsy. The tests were double-blind, so neither the dog handlers nor the experimenters knew which tubes were which.
The dogs correctly detected 99% of the lung cancer samples, and made a mistake with only 1% of the healthy controls. With breast cancer, they correctly detected 88% of the positive samples, and made a mistake on only 2% of the controls.