Learn about breast tumors--both benign and malignant--and what the different tumor grades mean.
Breast cancer tumors can differ in many ways. Learn about the types of tumors that can develop and how differences in tumor types affect prognosis.
Breast cancer most often begins with cells in the milk-producing ducts (invasive ductal carcinoma). Breast cancer may also begin in the.
Cancer starts when cells begin to grow out of control. (To learn more about how cancers start and spread, see What Is Cancer?) Breast cancer.