Dogs do as well as state-of-the-art screening tests at sniffing out people with lung or breast cancer. The research raises the possibility that trained dogs could detect cancers even earlier and might some day supplement or even replace mammograms and CT scans in the laboratory.

The dogs correctly detected 99% of the lung cancer samples, and made a mistake with only 1% of the healthy controls. With breast cancer, they correctly detected 88% of the positive samples, and made a mistake on only 2% of the controls.