Treatment of Mucinous Carcinoma of the Breast

You and your doctor will work together to develop a treatment plan for mucinous carcinoma of the breast. Pure mucinous carcinoma is easier to treat than invasive ductal carcinoma, so it may not require as much treatment — especially if the tumor is small and the cancer has not spread to the lymph nodes.

Your plan can include:

  • Surgery to remove the cancer and any affected lymph nodes. Possible procedures are:
    • Lumpectomy: The surgeon removes only the part of your breast containing the tumor (the “lump”) and some of the normal tissue that surrounds it. Your doctor may also remove some lymph nodes.
    • Total or simple mastectomy: Removal of the breast without removal of the axillary (underarm) lymph nodes. A sentinel node biopsy may be performed to check the node or nodes closest to the tumor for any signs of cancer spread.
    • Modified radical mastectomy: Surgery to remove the breast, the lining of the chest wall muscle, and some of the lymph nodes under the arm. Since pure mucinous carcinoma does not usually spread outside the original tumor, this type of mastectomy is not commonly done.
  • Adjuvant (additional) therapy, such as hormonal therapy and/or chemotherapy.
    • Hormonal therapy involves taking medications such as tamoxifen or an aromatase inhibitor, which either block the effects of estrogen or lower the amount of estrogen in the body. Almost all mucinous carcinomas are estrogen-receptor-positive, which means that hormonal therapy is likely to be an effective treatment. Adjuvant hormonal therapy is given to lower the chances of the breast cancer coming back.
    • Chemotherapy involves taking anti-cancer medicines in the form of a pill or directly into a vein. The medicines travel through the bloodstream to all parts of the body. The main goal is to destroy any cancer cells that may have broken away from the original tumor. There is some ongoing debate over how necessary chemotherapy is in cases of pure mucinous carcinoma.

    Many doctors base their recommendations about adjuvant therapy for mucinous carcinoma on the size of the tumor and whether or not there is evidence of cancer in the lymph nodes. Some general guidelines follow — but remember that individual doctors may have different opinions about whether additional treatment is needed for mucinous carcinoma.

    • If the tumor is smaller than 1 cm, with no cancer or just a very small amount of cancer in one lymph node: Hormonal therapy may be used, but no other treatment is needed after surgery.
    • If the tumor is between 1 and 2.9 cm in size, with no cancer or just a very small amount of cancer found in one lymph node: Chemotherapy may be considered along with hormonal therapy.
    • If the tumor is 3 cm or larger and there is spread to the lymph nodes: Chemotherapy is more strongly recommended, with the addition of hormonal therapy.

You and your doctor can discuss all of the risks and benefits of additional treatment beyond surgery. This decision may come down to what you and your doctor feel is best for you.

Most mucinous carcinomas test negative for receptors for the protein HER2/neu, so they usually would not be treated with Herceptin (chemical name: trastumuzab). Still, be sure to confirm with your doctor whether or not you are a candidate for this medication, which targets receptors for HER2.