The normal protocol for treating most cancers is to attack the tumor using a chemotherapeutic that kills the tumor cells. In head and neck squamous cell carcinoma, researchers theorized they could overcome treatment resistance and cancer spreading if they found a drug to also target cancer stem cells. In head and neck cancer, researchers believe cancer stem cells initially start the tumor growth, and serve as the metastasis mechanism. To test their theory, they induced cancer in mouse mouth tongues and fluorescent tagged a specific cancer stem cell protein, BMiI, which is responsible for stem cell self-renewal. They followed this protein, to see where it went. They discovered that BMil expressing stem cells invaded neighboring tissues and spread to other parts of the body. So by developing a drug that targets these cancer stem cells, they could improve treatment prognosis. Scientists then tested this theory by creating two treatment groups. One treated group received a standard anti-tumor drug. In this group, the cancer drug destroyed the tumor, but the cancer stem cells survived and spread to other tissues and parts of the body. The second group received the anti-cancer drug plus a drug that inhibits BMiI. This second group fared much better. The tumor disappeared and no cancer spread to other tissues . They further tested this theory by using another cancer drug, AP-I, which targets another crucial cancer stem cell protein. They saw the same results. This experiment shows that targeting tumor stem cells, in addition to the tumor, offers a better prognosis and prevention of cancer spreading in head and neck squamous cell carcinoma.