The goal of my research is to develop a powerful new molecular imaging technique that will allow me to characterize and monitor individual cells in the tumors of patients with breast cancer. Cancer treatments often fail because tumors contain cells with various genetic anomalies, and a drug that targets one subset of tumor cells might leave others unharmed, a situation that can lead to recurrence. As an independent investigator, I developed a method for labeling and visualizing the individual cells that make up a tumor. The approach couples light-deflecting particles with biological ID tags that are engineered to adhere to distinct cancer cells. Using this technique, I will catalog the different cell types present in human breast tumors that are grown in mice or removed from patients. Such imaging could allow clinicians to monitor the presence of all tumor cells over the course of treatment, optimizing a given therapy so that not a single cancer cell is left behind and cancer recurrence is avoided.