Triple negative breast cancer (TNBC) is the most aggressive and hard-to-treat form of breast cancer. Doctors have observed that TNBC patients with higher numbers of immune cells in their tumors seem to have better survival than those with fewer, but it's not well understood why. Damon Runyon Fellow Leeat Yankielowicz-Keren, PhD, and Dale F. Frey Breakthrough Scientist Sean C. Bendall, PhD, at Stanford University, are addressing this question by using a new imaging technique to precisely identify the type and location of immune and cancer cells in patient tumors. The researchers found that patients whose tumors showed immune cells crowded along defined borders, outside and within, were significantly more likely to survive their cancers with treatment. When a patient’s tumor was dispersed with immune cells throughout, the prognosis was far worse. The researchers are now hoping to use the technique to investigate responses to immunotherapy and to better understand how the immune composition of tumors changes over time. This research was published in Cell.