Find out about the different types of rarer breast cancers.
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.
About 5 out of 100 breast cancers (5%) are medullary breast cancers. The cancer cells tend to be bigger than in other types of breast cancer. And 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. It is more common in women who have inherited a faulty BRCA 1 gene.
Doctors treat medullary breast cancer in the same way as other types of invasive breast cancer. The outlook is generally better than for other types of invasive breast cancer.
About 2 in 100 breast cancers (2%) are mucinous breast cancers. This type of cancer tends to be slower growing than other types of breast cancers. 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 mixed type including mucinous and other types of invasive breast cancer.
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). If the tumour is small, you might not need your lymph nodes removed. The outlook for mucinous breast cancer is generally very good.
About 1 in 100 breast cancers (1%) are the tubular type. The cancer cells look like tubes when seen under a microscope.
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.
Fewer than 1 in 100 breast cancers (less than 1%) are adenoid cystic cancer. 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. It is a mixture of two cell types. The cells have started out as one cell type, such as an adenocarcinoma, but some of them have changed into another type of breast cell.
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.
Lymphomas of the breast contain both lymphoid tissue and breast tissue. If your doctor diagnoses lymphoma of the breast, they will arrange further tests for you. The tests check for lymphoma elsewhere in your body.
You have lymphoma treatment, rather than breast cancer treatment. Depending on the type and size of the lymphoma, you might have chemotherapy or radiotherapy, or both. You might also have surgery.
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 fi-loi-d-ees. It is also called cystosarcoma phyllodes. This breast tumour can be either cancerous (malignant) or non cancerous (benign). 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 but this is not common.
Under the microscope, papillary breast 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).
Doctors usually treat papillary breast cancer with surgery. These cancers usually grow slowly, and don’t usually spread to the lymph glands or other parts of the body.
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.
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.