loss of the breast.  Whether to perform the surgery is up to the woman. Some women may feel more
  comfortable avoiding surgery at an early stage and living with the risk. Others may feel otherwise.
• To diagnose or stage the disease  Although many non-surgical techniques can diagnose cancer accurately, 
  in most cases it is still necessary to have a sample of tissue to analyze. A surgeon can remove a small amount of
  tissue by inserting a very fine needle into the area of the tumor and drawing out a few cells to be examined under
  a microscope. This needle aspiration , or aspiration cytology , is the easiest and most comfortable technique
  used to obtain sample cells, but the very small amount of tissue involved may not be enough for an accurate
  diagnosis.
      When more tissue is needed, a larger needle can obtain a "core" of tissue for microscopic examination. If that
  sample is still not enough, a small operation, an incisional biopsy , may be performed to remove a portion of
  the tumor.  When the tumor is small, the surgeon might do an excisional biopsy, meaning that the entire lesion is
  removed rather than just a sample of it. This is very common with skin lesions, where the doctor has to know
  whether the lesion is a benign condition, malignant melanoma or some other skin cancer.
      To stage the disease properly a more formal operation may be needed to obtain tissue from other areas of the
  body. This is common with breast cancer where an axillary dissection, removal of lymph nodes under the arm,
  is usually performed in order to learn whether the cancer has spread to this area.
      It is important to remember that diagnostic surgery is just that—an operation designed merely to obtain
  tissue to confirm a diagnosis or to help plan adequate treatment. The goal is not to cure the cancer.