More than a millennium ago, the Persian physician Avicenna suggested that oral maladies could affect the entire body. Today, modern research is showing just how far those effects may reach—revealing that the microbes living on our teeth, tongue, and gums could offer clues to the early detection and prevention of disease throughout the body. A recent study in JAMA Oncology found that 27 species of oral bacteria and fungi were associated with a 3.5-fold higher risk of developing pancreatic cancer.