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On a work bench in a scientific research lab at the University of Pennsylvania in Philadelphia sits a box lined with gold and invisible nanotubes. A clear plastic tube runs through the middle of the box, and something like a pin cushion attached to blue and red wires hangs from its end. As air is piped through the clear plastic tube, signals are sent through the blue and red wires to a computer. Near the apparatus is a vial filled with blood providing a chemical scent the device can "sniff" through the clear plastic tube.
This device, termed an "electronic nose," is the invention of Dr. George Preti, an organic chemist who has been studying human scent for the last four decades. He has used his own nose and electronic sensors to identify odors that match functions of the human body. He has studied blood, sweat, tears, and other secretions to turn smell into a diagnostic test. And most recently he has been working on the question of whether ovarian cancer has a smell.
Diseases Cause Subtle Changes in the Ways People Smell
Human beings are constantly emitting odors. Tens of thousands of chemical waste products are released from the body in urine, feces, sweat, tears, or blood, or simply released into the air above the skin. Metabolic diseases like kidney failure or untreated diabetes alter the way the body breaks down chemicals into waste products and can make someone distinctively stinky.
The best known diagnostic sign of a condition called diabetic ketoacidosis is breath that smells like nail polish remover. The odor from the breath is noticeable, but the odor in the urine can be overpowering.
An inability to process the amino acid phenylalanine so that it spills over in the urine, phenylketonuria, makes people smell something like a damp basement or gym socks that weren't put in the laundry. People who lack a digestive enzyme and have the condition trimethylaminuria smell fishy. An overactive thyroid gland or excessive insulin production by the pancreas can lead to excessive perspiration which causes the well known body odor of bacteria thriving in sweat. And there is even a condition called ketoaciduria, in which the body lacks a group of enzymes to process the amino acids isoleucine, leucine, and valine, which makes the urine smell like maple syrup.
Why Try to Sniff Out Ovarian Cancer?
Before Dr. Preti's research, there was not, however, an easy way to detect the odor of ovarian cancer. There isn't any other easy, reliable way to detect the disease during its early, treatable stages, either. Doctors usually detect cancers by CT or MRI scans or by feeling for lumps. Because ovarian cancer causes no symptoms or only vague symptoms that overlap many other disease conditions during its early stages, doctors simply do not know to order the tests that would detect this kind of cancer before it has begun to spread.
Ovarian cancer is detected more or less by accident in its early stages about 15% of the time. When the cancer is detected in Stage 1, before it has invaded other tissues, about 92% of women live at least 5 years. But if ovarian cancer is detected at a later stage, only 27% of women live as long as 5 years after they are diagnosed.