Osa, a seven-year-old German Shepherd, is no ordinary dog: she has been trained to sniff out cancer. In a room at the University of Pennsylvania’s Working Dog Centre, she walks around a metal wheel fitted with eight spokes, which looks like a giant fidget spinner. Each spoke has a port at its end, which contains a speck of blood plasma – one is from a patient with early-stage ovarian cancer. Osa smells each port then stops at the cancerous sample and stares intently.
Scientists have trained Osa and two other medical-detection dogs to distinguish between plasma from normal patients, those with benign ovarian tumours and people with malignant ovarian cancer. Dogs are outstandingly accurate, says Cynthia Otto, the centre’s director, but doctors are not.
If detected promptly, 90% of ovarian cancers can be cured, but at present there is no means to diagnose it in its earliest stages. The symptoms – bloating, weight gain, abdominal discomfort – are generic and replicate many more benign problems, so most patients are diagnosed with ovarian cancer only in its later stages, when the survival rate drops to 20% of cases.
Using dogs to screen humans wouldn’t be an efficient use of their skills, says Otto. Instead, she is working with a physicist to develop a device designed to mimic dogs’ olfactory cells. When blood plasma is heated it produces a vapour that is blown against the sensor, which then “reads” the information it picks up. A computer algorithm analyses the output, which has so far been 100% accurate in identifying early-stage cancer samples. Although the sensors aren’t as fun to work with as Osa and her canine colleagues, their potential to save lives is not to be sniffed at.•