Doctors know that “PET scan” ordinarily refers to a diagnostic test used to detect cancer called a Positron Emmision Tomography. However there is a growing body of research suggesting that the other kind of pet — your dog — may also be useful in the detection of cancers and other diseases.
Everyone knows that dogs have a keener sense or smell than humans. According to www.aces.edu, ” A dog’s sense of smell is said to be a thousand times more sensitive than that of humans. In fact, a dog has more than 220 million olfactory receptors in its nose, while humans have only 5 million.”
That ability has lead dogs to play a vital roles in drug or bomb detection, and in search and rescue missions.
Researchers have also looked into whether dogs can use their sense of smell to detect breast and lung cancer. Dogs trained to identify the smell of the breath of patients with lung or breast cancer were able to detect those diseases with a 99% accuracy when directed to smell samples not previously encountered by the dogs during the training period.
The American Cancer Society estimates that, in 2014:
Five year survival rates for ovarian cancer are only about 45%. It has the highest mortality of all cancers of the female reproductive system. This reflects, in part, a lack of early symptoms and effective ovarian cancer screening tests. Thus, ovarian cancer is often diagnosed at an advanced stage, after the cancer has spread beyond the ovary.
Finding an way to diagnosis this disease earlier could make a huge difference in ovarian cancer survival.
Dr. Janos Tanyi, a University of Pennsylvania oncologist is working with Cindy Otto, director of the Penn Vet Working Dog Center. They have been training three dogs: McBaine, a springer spaniel; Ohlin, a Labrador retriever; and Tsunami, a German shepherd to detect the smell of ovarian cancer using blood and tissue samples taken from patients with the disease.
Here’s McBaine at work:
Marta Drexler, one of the patients who donated tissue to the study says that she is a textbook picture of the typical patient with ovarian cancer. She was detected late in her disease because she had no symptoms initially. But she is happy to be able to help this study, saying “To have the opportunity to help with this dreadful disease, to do something about it, even if it’s just a tiny little bit of something, it’s a big thing,”
Otto says of the project:
“If we can figure out what those chemicals are, what that fingerprint of ovarian cancer is that’s in the blood — or maybe even eventually in the urine or something like that — then we can have that automated test that will be less expensive and very efficient at screening those samples.”
But before you think that every lab in the country will need a resident dog to do the sniff testing, scientists have long been working on electronic devices, or e-noses, that can working in a manner similar to a dog (without the cost of dog food or down time for naps). Electronic noses include three major parts: a sample delivery system, a detection system, a computing system.
A traditional electronic nose has an array of chemical sensors, designed either to detect gases or vapors( technically called a headspace). The sensors are tuned to detect a family of chemicals, as opposed to an individual chemical. Each sensor is different, so when they are presented to a complex odor formed from many chemicals, each sensor responds differently to that odor. This creates a pattern of sensor responses, which the machine can be programmed to recognize.