Most of the roughly 40 trillion cells of your body have nearly identical copies of your genome—the DNA inherited from your parents, containing instructions for everything from converting food to energy to fighting off infections. Healthy cells become cancerous through harmful mutations in the genome. If a cell’s genome is damaged by ultraviolet light, for example, it can result in mutations that tell the cell to grow uncontrollably and form a tumor.
Identifying the genetic changes that cause healthy cells to become malignant can help doctors select therapies that specifically target the tumor. For example, about 25 percent of breast cancers are HER2-positive, meaning the cells in this type of tumor have mutations that cause them to produce more of a protein called HER2 that helps them grow. Treatments that specifically target HER2 have dramatically increased survival rates for this type of breast cancer.
Scientists can now readily read cell ...
