A mammogram is a low-dose x-ray image of your breasts. Mammograms are performed annually as a precautionary screening measure, or for women experiencing symptoms of breast cancer. Women need to have regular mammogram screenings because the sooner you locate cancer in its early stages, the more treatment options you have to fight it. Using your mammogram screening, your doctor can assess the presence, or lack thereof, of cancer up to three years before it can be felt during routine gynecological visits or self-examinations.