Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Breast Cancer ?
    ### Response:
    A mammogram can often detect breast changes in women who have no signs of breast cancer. Often, it can find a breast lump before it can be felt. If the results indicate that cancer might be present, your doctor will advise you to have a follow-up test called a biopsy.
    