Detection of cancer by sniffer dogs

Great advances are being made in the diagnosis of cancer with volatile organic compounds (VOCs) recognized as promising biomarkers. They can be found in the breath, urine, tissue, human breast milk and/or blood samples of oncology patients. The concentration and composition of VOCs are thought to be altered by cancer pathophysiology, leading to a cancer-VOC profile.

Dogs have an acute olfaction (a thousand times more sensitive than that of humans) and huge potential to learn through operant conditioning. The capability of dogs to identify human cancers based on a specific scent was first hypothesized in 1989 but, since then, few studies have been published.

This paper reviews the reports relating to the use of sniffer dogs in detecting various types of cancer, including melanomas, prostate, colorectal, ovarian, lung and breast cancers. One study concluded that, while there are some VOC alterations in melanoma cells, compared to healthy melanocytes, the reliability of VOCs as biomarkers in bladder and breast cancer is still unproven.

The paper’s main conclusion is that more rigorous studies need to be performed and that it is essential to select the right criteria for case/control groups and potential hormonal bias.  Differences in training approaches and environmental parameters should also not be overlooked.

Pirrone, F., Albertini, M., Olfactory Detection of Cancer by Trained Sniffer Dogs: A Systematic Review of the Literature, Journal of Veterinary Behavior (2017), doi: 10.1016/j.jveb.2017.03.004.