Sniffer Dogs On The Fight Against Cancer
Written by Elyse Ehlert
Edited by Chloe Chou
September 27th, 2023
Edited by Chloe Chou
September 27th, 2023
Research
In today’s modern world, researchers and scientists have only become more and more innovative in their approaches to worldwide medical issues such as cancer and heart disease. According to a German study published in 2021, dogs too may soon be joining the fight (Feil et al., 2021). Between 2016 and 2017, researchers trained dogs to identify breath and urine samples taken from lung cancer patients, and the results were striking. Overall, the dogs were able to correctly detect cancer 97.6% of the time. As the World Health Organization states, lung cancer is one of the most prevalent newly diagnosed cancers each year (2.2 million worldwide in 2020), so a noninvasive testing approach such as this could be a game-changing tool in early detection (WHO, 2022). As a reference, current tests such as CT scans or surgical biopsies are often costly and invasive (NHS, 2022).
Due to dogs’ advanced olfactory system, they can detect a multitude of smells beyond the range of the human nose, including cancer causing volatile organic compounds (VOCs). These compounds can indicate the presence of cancer and can be used as biomarkers. With this knowledge, researchers used classical conditioning to train a labrador retriever dog over the course of a year to identify cancer samples versus control (non-cancer patient) samples. Breath and urine samples were taken from patients with confirmed cases of lung cancer, as well as healthy individuals in order to provide a control group for the dog. After the conditioning phase, samples were collected from new patients so that no subjects that the dog had been previously conditioned to would be a part of the study phase.
The study was conducted in a double-blinded manner (the researchers and the dog would not know whether the sample was in fact a cancer sample until after the test trials). 205 control samples and 41 cancer samples were presented to the dog. After the results were collected, it was discovered that the dog had correctly detected cancer in the urine samples at a rate of 87.8% and at a rate of 78% in breath samples. These combined results however, meant that 40 out of the 41 cancer samples were correctly identified, or 97.6%. For dogs to detect cancer with such high accuracy in this non-invasive, non-complex testing manner, is astounding.
Though more studies confirming these outcomes would be beneficial, this study has great initial promise. Currently, there are no early detection tests available for lung cancer or recommended screening tools (AWMF, 2018). Training dogs to detect cancers such as this is a time-intensive process, as shown by the year long conditioning period. However, as the medical world continues to develop and innovate, cancer-sniffing dogs could prove to be an invaluable aid in better patient care and cancer screening.
References
Feil, C., Staib, F., Berger, M. R., Stein, T., Schmidtmann, I., Forster, A., & Schimanski, C. C. (2021). Sniffer dogs can identify lung cancer patients from breath and urine samples. BMC Cancer, 21(1). https://doi.org/10.1186/s12885-021-08651-5
Leitlinienprogramm Onkologie. (2018, February). S3-Leitlinie Prävention, Diagnostik, Therapie und Nachsorge des Lungenkarzinoms [Review of S3-Leitlinie Prävention, Diagnostik, Therapie und Nachsorge des Lungenkarzinoms]. AWMF online. https://register.awmf.org/assets/guidelines/020-007OL_l_S3_Lungenkarzinom_2018-03.pdf
Lung cancer - Diagnosis. (2017, October 23). Nhs.uk. https://www.nhs.uk/conditions/lung-cancer/diagnosis/#:~:text=A%20chest%20X%2Dray%20is
National Cancer Institute. (2019). NCI Dictionary of Cancer Terms. National Cancer Institute; Cancer.gov. https://www.cancer.gov/publications/dictionaries/cancer-terms/def/biomarker
World Health Organization. (2022, February 3). Cancer. World Health Organization. https://www.who.int/news-room/fact-sheets/detail/cancer
Image Source: “Happy woman training dog and sitting on chair, canine, friend, retriever flat illustration” by pch.vector licensed under freepik.com’s free license