Dogs Can Detect Ovarian Cancer

Ovarian cancer is, as we have reported before, difficult to diagnose, so that the start of treatment is often delayed to a point when the results are poor. There have been recent studies suggesting that dogs have successfully detected cancer through scent, so Swedish researchers decided to study the possible role of dogs in assisting diagnosis of this particular tumor. They report their results in the journal Integrative Cancer Therapies.

The scientists trained dogs to distinguish different types and grades of ovarian cancers, including borderline tumors, from healthy control samples. Frozen pathology samples of tumor were thawed, along with other gynecological tumors and normal tissues, such as abdominal fat and muscle, and pieces placed in glass containers covered with a porous lid enclosed in a wooden box. The dog, a 4-year-old schnauzer, was trained twice a week for a year. In the final ‘double-blind’ testing - both the handler and an independent judge were blinded as to the nature of the samples being tested – a positive response was made by the sniffer dog scratching the target box with his foreleg.

Ovarian cancer samples from 20 individual patients were used as targets, along with 80 control samples. The dog correctly identified all the cancer samples (20 out of 20, giving a test sensitivity of 100%), and correctly recognized 78 of the 80 controls - one fat and one muscle sample were incorrectly selected as a positive. This yielded a test specificity of 97.5%.

The researchers claim that this study provides the first evidence of a specific odor emitted by ovarian carcinomas. Moreover, early stage and low-grade tumors were also detected, suggesting that the odor emitted is the same for all grades of ovarian cancer. But they stop short of proposing that dogs could be used in clinical practice. As “living instruments’, they would be open to influence by many factors before and during the test, so that accuracy rates might vary. However, in a research setting, they may be useful in exploring this property of malignancies, leading perhaps to innovative “non-living instruments” that could shift the diagnosis of ovarian cancer to earlier stages.