Dogs could help detect breast cancer through smell.

A French group called Kdog is pursuing the non-invasive technique, which consists of a trained dog smelling a bandage that has been held against the affected breast.

Two German shepherds received six months of training on samples collected from 31 patients. Researchers worked on the assumption that breast cancer cells have a distinguishing smell.

After the training, researchers put Thor and Nykios to the test. Each of the 31 bandages—taken from different patients than the ones the dog had been trained on—was placed in a box attached to a large cone. The dogs could stick their noses into the cone to smell what was in the box. Three bandages that had been used by women with no cancer were also placed in boxes, giving the dogs four boxes total to choose from.

In the first round of testing, the dogs detected 28 of the 31 cancerous bandages. On the second round, they detected 100 percent of the affected bandages.

This testing is what’s called the proof-of-concept phase for Kdog. The next step will be a clinical trial with more patients and different dogs.

The researchers hope to develop this non-invasive method to provide a cost-effective alternative for countries where mammograms are more difficult to come by.

Other research has been done to see if dogs can smell different kinds of cancer. One study in 2004 found that dogs could distinguish patients with bladder cancer based on the smell of the urine at rates higher than through chance alone (success rate of 41%). In a study from 2006, dogs smelled breath samples of people with lung cancer and those without, resulting in a success rate of 99%. Another study in 2011 tested dogs smelling breath to detect lung cancer, resulting in a sensitivity of 71%, detecting lung cancer independently of COPD and the presence of tobacco smoke.

Photo credit: © iStock/BigDuckSix