Find out about the different rare types of breast cancer.
Grouping breast cancers
Doctors have developed ways of grouping breast cancers into different types. They sometimes call rarer breast cancers special type and the more common breast cancers no special type.
Most breast cancers are invasive carcinoma - no special type. You may see this written as NST or NOS (not otherwise specified).
Special type breast cancers have cells with particular features. As well as the rare cancers listed here, lobular breast cancer is also classed as a special type.
Between 2 and 5 out of every 100 breast cancers are medullary breast cancers (2 to 5%). They occur more often in younger women and in women who have inherited a faulty BRCA 1 gene.
The cancer cells tend to be bigger than in other types of breast cancer. When doctors look at these cancers under a microscope they can see a clear boundary between the tumour and the normal tissue. This type of breast tumour is also unusual because it contains white blood cells.
Doctors treat medullary breast cancer in the same way as other types of invasive breast cancer. The outlook is generally very good for this type.
Between 1 to 4 out of every 100 breast cancers are mucinous breast cancers (1 to 4%). This type of cancer tends to be slower growing than other types and occurs more often in older women. It is less likely to spread to the lymph nodes.
Mucinous breast cancers have this name because the cancer is made up of a large amount of mucin. It can be a pure mucinous cancer or it can be a mix of mucinous and other types.
Doctors usually treat mucinous cancers in the same way as other types of breast cancer. They remove the cancer with surgery, either taking away the whole breast (mastectomy) or part of the breast (a wide local excision). You might have a test called a sentinel node biopsy to see if the cancer has spread to the lymph nodes.
The outlook for mucinous breast cancer is generally very good.
About 2 out of every 100 breast cancers are the tubular type (2%). The cancer cells look like tubes when seen under a microscope. This type occurs more often in older women and the tumour is usually very small when diagnosed. It sometimes spreads to nearby lymph nodes.
Treatment is the same as for other types of invasive breast cancer. Tubular breast cancer is less likely to come back after treatment than some other types. So, the outlook is generally good.
Less than 1 in 100 breast cancers are adenoid cystic cancer (less than 1%). This type of cancer is also sometimes called a cribriform cancer. It is a cancer type that is more often diagnosed in the salivary glands but some occur in the breast tissue.
Adenoid cystic breast cancer tends to be slow growing. Doctors usually recommend surgery. Most women don’t need to have the whole breast removed (a mastectomy). Instead, your doctor will just remove the area of the cancer. This operation is called a wide local excision.
The cancer rarely spreads elsewhere in the body. So you don't usually need to have your lymph nodes removed. And the risk of this type of tumour coming back is low, so the outlook is good.
This type of breast cancer is very rare and makes up less than 1 out of 100 breast cancers (less than 1%). It usually occurs between the ages of 47 to 61 and is relatively more common in Hispanic or black women.
Doctors treat metaplastic cell cancers in the same way as other breast cancers. You might have surgery, chemotherapy and radiotherapy.
Some metaplastic breast tumours are triple negative. This means that the cancers don’t have receptors for oestrogen, progesterone or HER2. So hormone therapy or biological therapy isn't helpful for these cancers.
Metaplastic breast cancer tends not to spread to the lymph glands but it is more likely to spread to other parts of the body than other types of breast cancer. The outlook can then be poorer.
Non Hodgkin lymphomas of the breast are rare and make up less than 1 in 100 breast cancers (less than 1%).
The most common types are B-cell lymphomas such as diffuse large B-cell lymphomas and extranodal marginal zone lymphomas. A less common type is peripheral T-cell lymphoma (PTCL).
A type of lymphoma called breast implant-associated ALK-negative lymphoma can occur (i-ALCL) in a small number of women who have breast implants. The first sign might be a collection of fluid around the breast implant called a seroma. In this case the lymphoma hasn't spread into other areas of the breast. It is called in situ lymphoma. The implant is removed and often no further treatment is needed. The outlook is excellent for this type.
In some women the lymphoma can show as a lump in the breast. This type is called infiltrative i-ALCL and it might also spread to the lymph nodes. After removing the implant the treatment is usually chemotherapy or somtimes radiotherapy. The outlook is not so good for this type.
Basal type breast cancer has particular genetic changes in the cells. The p53 gene is damaged (mutated) or lost. The cells make large amounts of a protein called cytokeratin 5/6.
Basal type breast cancers are often triple negative. This means that they don't have many receptors for oestrogen, progesterone, or HER2. So, hormone therapies and biological therapies don't work for most basal type cancers.
Doctors use other treatments, such as surgery, chemotherapy and radiotherapy, instead.
Phyllodes is pronounced fill-oy-dees. It is also called cystosarcoma phyllodes. This breast tumour can be either cancerous (malignant) or non cancerous (benign). It tends to occur in middle aged women or older. If cancerous, it might spread into the lymph nodes but this is rare.
Surgery is the main treatment. Sometimes radiotherapy or chemotherapy are also used.
Papillary breast cancer makes up less than 1 in 100 breast cancers (less than 1%). Under the microscope, the cancer cells look a bit like the shape of a fern. Papillary tumours tend to affect older women. They can also be non cancerous (benign).
The usual treatment is surgery. These cancers usually grow slowly, and don’t usually spread to the lymph glands or other parts of the body. The outlook is very good.
Coping with a rare type of breast cancer
Coping with a diagnosis of cancer can be difficult, both practically and emotionally. It can be especially difficult if you have a rare cancer. Being well informed about your cancer and its treatment can make it easier to make decisions and cope with what happens.
Talking to other people who have the same thing can help. But it can be hard to find people who have had a rare type of cancer.
Cancer Chat is Cancer Research UK’s discussion forum. It is a place for anyone affected by cancer. You can share experiences, stories and information with other people who know what you are going through.
Support and information
The Rare Cancers Alliance give support and information to people with rare cancers.
Cancer Research UK nurses
Trials and research
There may be fewer clinical trials for rare types of cancer, than for more common types. It is hard to organise and run trials for rare cancers. Getting enough patients is critical to the success of a trial. The results won't be powerful enough to prove that one type of treatment is better than another if the trial is too small.
The International Rare Cancers Initiative (IRCI) aims to develop more research into new treatments for rare cancers. They are designing trials that involve several countries so that more people will be available to enter trials.