Many women find their own breast cancers, either by accident or from a breast self-exam. Sometimes breast cancers are found at a routine physical exam or on a screening mammogram. A mammogram is a special X-ray of the breast to look for breast cancer. Mammograms usually detect cancers before a lump can be felt. They detect most cancerous growths in the breasts. Mammograms are also used to check lumps that are found in a physical exam.

Most breast lumps are not cancer. Often they are fluid-filled cysts in the breast tissue that get larger and smaller with the menstrual cycle. But any lump that does not go away should be checked. Other ways of checking lumps are by ultrasound scans, needle or surgical biopsy, or magnetic resonance imaging (MRI). These tests may be done even if the lump is not seen on the mammogram.