Learning About Metaplastic Breast Cancer

Metaplastic breast cancer is a rare type of breast cancer. About 1% of all breast cancers are this type. It is a fast-growing (aggressive) cancer and is more likely to spread to other parts of the body. It is also more likely to come back after treatment.

In metaplastic breast cancer, the cancer cells in the breast change into cancer cells that aren't normally found in the breast.

Metaplastic breast cancer is most often triple-negative. This means the cancer cells don’t have any of the three common receptors for estrogen, progesterone, or HER2 protein. Triple-negative breast cancer can be harder to treat.

This type of breast cancer is less likely to spread to the lymph nodes, but it can spread through the bloodstream.

You are more at risk of having this cancer if you are:

• Age 50 or older.
• Post menopause.
• African American.

Metaplastic breast cancer may not cause symptoms at first. It may be found with a screening mammogram. As a tumor grows, symptoms may include:

• A new lump in the breast.
• Breast swelling or changes in size or shape.
• Skin changes such as redness, dimpling, or thickening.
• Fluid from the nipple.
• A nipple turned inward (inversion).

Because early breast cancer may not cause symptoms, it’s important to have screening mammograms. These can help detect breast cancer earlier, when treatment works better. Talk with your doctor about when to get screened.

Doctors use several tests to diagnose breast cancer. They include:

• Mammogram. This is an X-ray of the breast. It can help show abnormal areas that may not be felt during a physical exam.
• Ultrasound. Breast ultrasound uses sound waves to create images of the breast tissue. It can help doctors learn more about an abnormal area seen on a mammogram or felt during an exam.
• Biopsy. A biopsy is needed to confirm a cancer diagnosis. During a biopsy, a small sample of tissue is removed. The tissue is examined under a microscope to see if it has cancer cells.

A metaplastic breast cancer tumor may be larger at diagnosis than other types of breast cancer. This is due to faster growth.

After diagnosis, tests will be done on the cancer cells. These tests help guide treatment choices. The lab will also look at what kinds of cancer cells the cancer has turned into.

There are several kinds of metaplastic breast cancer cells, such as:

• Mixed metaplastic carcinoma.
• Metaplastic carcinoma with mesenchymal differentiation.
• Squamous cell carcinoma.
• Spindle cell carcinoma.

Tests will also see how abnormal the cancer cells look compared to regular cells (the grade of the cancer). Cancer cells that look more abnormal (have a higher grade) grow faster.

And you may have tests to see if or how far the cancer cells have spread in your body. This may include a positron emission tomography (PET) scan. A PET scan uses a CT scan or MRI plus a radioactive substance to find cancer cells around your body. You may also have a bone scan to see if any cancer cells are growing in your bones.

The types of treatment that your doctor advises will be based on these factors:

• The size of the tumor.
• How abnormal the cancer cells look (grade).
• How far they have spread (stage).
• What receptors they have.
• Your overall health.

The treatment options can include:

• Surgery. Surgery options include:
  • Lumpectomy. This is done to remove the tumor and a small amount of surrounding tissue.
  • Mastectomy. This is done to remove all or most of the breast.
• Radiation therapy. This is the use of radiation to kill cancer cells. It may be used before surgery to shrink a tumor or after surgery to kill any remaining cancer cells.
• Chemotherapy (chemo). This is the use of medicines to kill cancer cells throughout the body. Your doctor will decide if chemo may help based on the tumor grade and stage. Chemo tends to work less well on metaplastic breast cancer.
• Immunotherapy. This is the use of medicines to help the immune system attack and kill cancer cells.
• Targeted therapy. This may be an option in some cases depending on the test results on the cancer cells.
• Clinical trial therapies. Research is ongoing for the best ways to treat this cancer. Talk with your doctor to see if you can be part of a clinical trial.

Hormone therapy is not often used. This is because metaplastic breast cancer often does not use estrogen or progesterone to grow.

A diagnosis of metaplastic breast cancer can feel overwhelming. Support is available for both patients and caregivers.

Helpful resources include:

• Breast cancer support groups.
• Counseling or therapy.
• Patient advocacy organizations.
• Talking with your care team so that they can connect you to services.