Development of an Early Cancer Detection Method Using the Olfaction of the Nematode Caenorhabditis elegans

Early detection and treatment are important for the successful eradication of various cancers; therefore, the development of economical, noninvasive novel cancer screening systems is critical. Previous reports using canine scent detection have demonstrated the existence of cancer-specific odors. However, it is difficult to introduce canine scent recognition into clinical practice because of the need to maintain accuracy. In this study, we developed a Nematode-Nose (N-NOSE) test using Caenorhabditis elegans to provide a novel, highly accurate cancer detection system that is economical, painless, rapid, and convenient. We demonstrated that wild-type C. elegans displayed attractive chemotaxis toward human cancer cell secretions, cancer tissues, and urine from cancer patients but avoided control urine. In parallel, C. elegans olfactory neurons showed a significantly stronger response to urine from cancer patients than to control urine. In contrast, G protein alpha mutants and animals with ablated olfactory neurons were not attracted to urine from cancer patients, suggesting that they sense odors in urine. We tested 242 samples to measure the performance of the N-NOSE test and found that the sensitivity was 95.8%, which is markedly higher than that of other existing tumor markers. Furthermore, the specificity was 95.0%. Importantly, this test could detect various cancer types tested at the early stage (stage 0 or 1). C. elegans scent-based analyses therefore might provide a new strategy for the detection and study of disease-associated scents.