Odor detection of cancer cell metabolites by scent-detection dogs

Abstract

Dogs have a superior olfactory system; thus, they have been trained and used to detect various nonbiological and biological scents. In addition, many studies have recently reported dogs’ ability to detect the odor of certain cancers or cancer cells. A previous study documented that a dog trained to detect a certain malignant cancer cell could also detect another, unfamiliar malignant cancer cell well, implying that these two cancer cells share a certain specific odor. Thus, given the hypothesis that malignant cancer cells of different origins may contain a common cancer-specific odor, the purpose of the present study was to evaluate odor detection ability for various cancer cells (prostate, lung and breast cancer) by dogs trained on prostate cancer cells. Two dogs were trained and participated in the tests. Sensitivity, specificity and the value of area under the curve (AUC) by receiver operating characteristic curve analysis were evaluated. According to the AUC value, the two dogs showed excellent and perfect detection abilities in detecting the odor of a trained prostate cancer cell (PC3), respectively. Both dogs also showed good detection ability for another, unfamiliar prostate cancer cell (LNCaP-LN3). When evaluating the detection ability for lung (A549) and breast (MCF-7) cancer cells, the two dogs showed excellent and good detection abilities, respectively. In conclusion, it is presumed that a certain common cancer-specific odor exists in cancerous cells when compared with normal cells. Scent-detection dogs have promising potential in training for cancer detection. Further study is needed to determine whether the detection ability of dogs trained to cancer cells affects the detection ability for real cancer.