Dogs, bees, and fruit flies are some animals that can literally sniff out cancer. It's hoped that by understanding how these animals are able to make these positive identifications, scientists can then develop an “electronic nose” which would provide a fast, noninvasive screening for cancers. A new study presented by lead author Gian Luigi Taverna of the Humanitas Research Hospital in Milan has provided evidence of two dogs able to sniff out prostate cancer with exceptional accuracy. The findings were presented Sunday, May 18th at the Annual Meeting of the American Urological Association in Orlando, Reuters reported.

As early detection is critical for overcoming cancer, it is best to discover anomalies before patients become symptomatic, which isn’t always feasible. Certain diseases, such as pancreatic or ovarian cancer, do not become symptomatic until 5-year survival rates are dangerously low. Processing blood or urine tests are slow and costly, making them a poor choice for a routine screening.

Certain animals have advanced olfactory senses which allow them to smell and identify the volatile organic compounds (VOCs) associated with certain cancers when exposed to breath or urine samples. Animals like dogs can be trained to respond in a certain way to indicate the presence of disease, while some fruit flies have been genetically engineered to glow when they find certain VOCs.

The Italian researchers used two German Shepherds who had previously received training to seek out bombs. After five months of positive reinforcement training, the dogs were tested on 430 urine samples and were tasked with identifying prostate cancer. Of the 430 samples, 200 came from patients with known prostate cancer, and the other 230 served as a control. One dog was able to identify the prostate cancer patients with 100% accuracy and the controls with 98% accuracy. The other dog also did quite well, by identifying disease with 98.6% accuracy and ruled out controls 96.4% of the time. Further study will be needed to verify these findings, such as using different trained dogs and different samples.

While your family doctor probably isn’t likely to put a dog on staff to come around and sniff you during your annual check up, scientists have a lot to learn about how these VOCs are sensed. Dogs have about 40 times as many olfactory cells than humans, leaving us a lot to learn about how these trace odors are perceived. Currently, different laboratories around the world are using animals to help detect bladder, ovarian, breast, lung, and prostate cancer. The end goal of this field of research is to develop a device that blends mass spectrometry and gas chromatography that can analyze laboratory samples quickly and easily.