Breast cancer diagnosis

The series of tests needed to evaluate a possible breast cancer usually begins when a mass or abnormal calcifications are detected on a screening mammogram, or a lump or nodule in the breast is discovered during a clinical or self-examination. Some of the following diagnostic tests and procedures may be used:

Imaging tests

Imaging tests produce pictures of the inside of the body. The following imaging tests may be done to learn more about a suspicious area found in the breast during screening.

  • Diagnostic mammography: This is similar to screening mammography, except that more pictures of the breast are taken. It is often used when a woman is experiencing worrisome signs, such as a lump or nipple discharge. Diagnostic mammography may also be used if something suspicious is found on a screening mammogram.
  • Ultrasound: An ultrasound uses sound waves to create a picture of the breast tissue. The sound waves echo differently when bouncing off abnormal tissue and healthy tissue. An ultrasound can distinguish between a solid mass, which may be cancer, and a fluid-filled cyst, which is usually not cancer.
  • MRI: An MRI uses magnetic fields to produce detailed images of the body. A special dye is given before the scan to help create a clear picture of possible cancer. This dye can be injected into a patient’s vein or given as a pill to swallow. A breast MRI may also be used after a woman has been diagnosed with cancer to check the other breast for disease or to determine how much the cancer has grown or spread throughout the breast. It may also be used before surgery to determine if chemotherapy is effectively shrinking the tumor.


During a biopsy, a small amount of tissue is removed and examined under a microscope by a pathologist. Other tests can suggest that cancer is present, but only a biopsy can make a definite diagnosis. There are different types of biopsies, which are classified by the technique and/or size of the needle used to collect the tissue sample.

  • Fine needle aspiration biopsy: Uses a thin needle to remove a small sample of cells.
  • Core needle biopsy: Uses a larger needle to sample breast changes felt by the doctor or pinpointed by ultrasound or mammogram. Sometimes, the biopsy needle is guided by an MRI or CT scan. Another way to do a core biopsy is known as vacuum-assisted. Local anesthesia is used to lessen a patient’s discomfort during the procedure.
  • Surgical biopsy: In rare cases, surgery is needed to remove all or part of the lump for testing. Most often, the surgeon removes the entire mass or abnormal area as well as a surrounding margin of normal breast tissue.
  • Image-guided biopsy. A needle is guided to the site of the abnormal growth with the help of an imaging technique, such as mammography, ultrasound or MRI. An image-guided biopsy can be done using a fine needle or core needle (see above), depending on the amount of tissue being removed. Imaging tests may also be used to help conduct a biopsy on a lump that can be felt, to help find the best location.
  • Sentinel lymph node biopsy: To determine if there is cancer in the lymph nodes near the breast, a surgeon injects a radioactive substance and/or a blue dye near the tumor to locate the position of the sentinel lymph node. Once the sentinel lymph node is located, the surgeon makes a small incision in the overlying skin and removes the node. The sentinel node is then checked for the presence of cancer cells by a pathologist. If cancer is found, the surgeon may remove additional lymph nodes, either during the same biopsy procedure or during a follow-up surgical procedure. This procedure is usually done at the same time the primary tumor is removed. However, the procedure can also be done either before or after the removal of the tumor.