Metaplastic breast cancer is a rare type of breast cancer accounting for less than 1% of breast cancers.
It’s an invasive cancer, which means it has the potential to spread to surrounding breast tissue and to other parts of the body.
In this type of breast cancer the cancer cells change (transform) from one cancer cell type into another.
Metaplastic breast cancers are usually divided into two main groups (called purely epithelial and mixed epithelial). There are further types of metaplastic breast cancer within these groups.
The symptoms of metaplastic breast cancer are similar to those of invasive ductal breast cancer. These can include a change in the size of the breast, a lump or thickening of the skin, breast pain, changes to the nipple and puckering or dimpling of the skin.
Routine breast screening can often pick up cancer before there are any symptoms. Therefore some women will be diagnosed with metaplastic breast cancer after attending breast screening without having any of the symptoms described above.
Metaplastic breast cancer is diagnosed using a range of tests including a mammogram (breast x-ray) and an ultrasound scan, followed by a fine needle aspiration (FNA) and/or core biopsy.
Find out more about diagnosing breast cancer.
As with all types of breast cancer, the features (such as size and grade) of your metaplastic breast cancer will affect what treatments you may be offered. However, metaplastic breast cancer is more likely to be triple negative.
Find out more about triple negative breast cancer.
Breast surgery is usually the first treatment for metaplastic breast cancer.
This may be:
- breast-conserving surgery, also known as wide local excision or lumpectomy which is the removal of the cancer with a margin (border) of normal breast tissue around it
- mastectomy, which is the removal of all the breast tissue including the nipple area.
The amount of tissue removed depends on the area of the breast affected, how big the cancer is in relation to the size of your breast, whether more than one area in the breast is affected. Your breast surgeon will discuss this with you.
If you have breast-conserving surgery, it’s important that a clear margin of tissue is taken from around the cancer. If a clear margin of tissue is not seen when the area removed is examined under the microscope, sometimes a second operation is needed.
If you’re going to have a mastectomy, you’ll usually be able to have breast reconstruction either at the same time as your mastectomy (immediate reconstruction) or at a later date (delayed reconstruction).
Surgery to the lymph nodes
Your specialist team will want to check if any of the lymph nodes (glands) under the arm (the axilla) contain cancer cells. This helps them decide whether or not you will benefit from additional treatment after surgery.
To do this, your surgeon is likely to recommend an operation to remove either some (a lymph node sample or biopsy) or all of the lymph nodes (a lymph node clearance).
Sentinel lymph node biopsy is widely used for people whose tests before surgery show no evidence of the lymph nodes containing cancer cells. It identifies whether the first lymph node (or nodes) is clear of cancer cells. If it is, this usually means the other nodes are clear too, so no more will need to be removed.
If the results of the sentinel lymph node biopsy show that the first node or nodes are affected, you may be recommended to have further surgery or radiotherapy to the remaining lymph nodes. However, spread to the lymph nodes under the arm is uncommon in metaplastic breast cancer, compared to other invasive breast cancers. Your surgeon will discuss whether having a sentinel node biopsy is an option for you.
Find out more information about surgery to the lymph nodes.
Adjuvant (additional) treatment
After surgery you may need other treatments. This is called adjuvant therapy and can include:
- hormone therapy
- targeted therapy.
The aim of these treatments is to reduce the risk of breast cancer returning in the same breast or developing in the other breast, or spreading somewhere else in the body.
Sometimes chemotherapy or hormone therapy may be given before surgery. This is known as neo-adjuvant or primary therapy.
Chemotherapy will be recommended for many people with metaplastic breast cancer.
Whether or not you’re offered chemotherapy depends on various features of the cancer including its size, its grade and whether the lymph nodes are affected.
If you have breast-conserving surgery you will usually be offered radiotherapy to the breast to reduce the risk of the cancer coming back in the same breast. Sometimes you may be offered radiotherapy to the nodes under your arm.
In some circumstances, you may be recommended to have radiotherapy to the chest wall after a mastectomy, for example if some lymph nodes under the arm are affected.
Hormone (endocrine) therapy
Hormone therapy will only be prescribed if your breast cancer has receptors within the cell that bind to the hormone oestrogen, known as oestrogen receptor positive or ER+ breast cancer.
All breast cancers are tested for oestrogen receptors using tissue from a biopsy or after surgery. When oestrogen binds to these receptors, it can stimulate the cancer to grow.
Metaplastic breast cancer is more likely to be oestrogen receptor negative (ER–). If this is the case, then hormone therapy will not be of any benefit.
Find out more about when hormone therapy is given.
Targeted therapies (sometimes called biological therapies)
This is a group of drugs that block the growth and spread of cancer. They target and interfere with processes in the cells that cause cancer to grow.
The most widely used targeted therapy is trastuzumab (Herceptin). Only people whose cancer has high levels of HER2 (HER2 positive) will benefit from having trastuzumab. HER2 is a protein that makes cancer cells grow.
There are various tests to measure HER2 levels which are done on breast tissue removed during a biopsy or surgery. Metaplastic breast cancer tends to be HER2 negative meaning that trastuzumab will not be of any benefit.
When breast cancers are HER2 negative, oestrogen receptor negative and progesterone receptor negative, the cancer is referred to as being ‘triple negative’.
Coping with metaplastic breast cancer
Everybody responds differently to their diagnosis and has their own way of coping. However, you may feel alone, particularly as metaplastic breast cancer is a rare type of breast cancer. There are people who can support you so don’t be afraid to ask for help. Talk to your breast care nurse or contact our Support Line.