Researchers used small, healthy breast tissue samples donated by women through the Komen Tissue Bank—the only place in the world that collects this kind of tissue just for research. They used a special method to look at each cell one at a time and found 23 different types of breast cells. This gave them a clear picture of what normal breast tissue looks like.
Next, they checked about 3,000 breast cancer samples and found that most tumors matched mature breast cells, while about 1 in 5 matched younger, developing cells—and one of those younger cell types turned out to be linked to a more aggressive form of cancer. They also discovered two genes, TBX3 and PDK4, that appear alongside estrogen in normal breast cells. By looking at over 550 estrogen-positive tumors, they saw that these genes helped predict which cancers were more likely to come back, which means doctors might one day use them to guide treatment decisions.
