Your care team uses several tests to look at breast tissue and guide the next steps. A physical exam checks your breasts and armpits for lumps or anything unusual. Imaging tests—a mammogram (an X-ray of the breast), an ultrasound, or an MRI—let providers see inside the breast. A biopsy removes a small piece of tissue so it can be studied closely. Blood chemistry tests measure substances like proteins and enzymes in your blood. If cancer is found, a sentinel lymph node biopsy checks whether cancer has reached nearby lymph nodes. Some people also have genetic tests or hormone receptor tests on the cancer cells. Ask your care team which tests you need and why.