Primary breast cancer is breast cancer that hasn’t spread beyond the breast or the lymph nodes (glands) under the arm.
Breast cancer starts when cells in the breast begin to divide and grow in an abnormal way. Breast cancer is not one single disease and there are several types.
It can be diagnosed at different stages and can grow at different rates. This means people can have different treatments, depending on what will work best for them.
Breasts are made up of lobules (milk-producing glands) and ducts (tubes that carry milk to the nipple). These are surrounded by glandular, fibrous and fatty tissue. This tissue gives breasts their size and shape.
Breasts contain a network of thin tubes called lymph vessels. These are connected to the lymph nodes (glands) under the arm.
There are different types of breast cancer.
Breast cancer can be non-invasive (also called ‘in-situ’) or invasive.
Non-invasive breast cancer
Non-invasive breast cancer has not yet developed the ability to spread, either within the breast or to another part of the body.
Ductal carcinoma in situ (DCIS)
Ductal carcinoma in situ (DCIS) is an early type of breast cancer, sometimes called intraductal, non-invasive or pre-invasive cancer.
The cancer cells are inside the milk ducts (known as ‘in situ’) and have not yet developed the ability to spread, either through the ducts into surrounding breast tissue or to other parts of the body.
If DCIS is not treated, the cells may develop the ability to spread and become invasive breast cancer.
Invasive breast cancer
Most breast cancers are invasive. Invasive breast cancer has the potential to spread to other areas of the body. This doesn’t mean the cancer has or will spread to another part of the body, just that it is a possibility. Treatments aim to reduce the risk of this happening.
Invasive ductal breast cancer (of no special type)
Most breast cancers are invasive ductal breast cancers. Breast cancer cells started in the milk ducts and have spread to the surrounding breast tissue.
It’s also called breast cancer of no special type (NST) or not otherwise specified (NOS). This is because when the cancer cells are looked at under a microscope they have no distinct features that class them as a particular type.
Invasive lobular breast cancer
This is the second most common type of breast cancer, where cancer cells in the lobules (milk-producing glands) have spread into the surrounding breast tissue.
Inflammatory breast cancer
Inflammatory breast cancer is a rare, faster-growing type of breast cancer. It is called inflammatory because the skin of the breast looks red and inflamed. This is caused by breast cancer cells blocking the tiny lymph channels in the breast and the skin.
Paget’s disease of the breast
Paget’s disease of the breast is an uncommon type of breast cancer that causes change to the skin of the nipple, similar to eczema.
Other types of breast cancer
There are several other rare special types of breast cancer. These include:
- mucinous (also called colloid breast cancer)
- malignant phyllodes
Treatment for primary breast cancer can include:
- hormone therapy
- targeted (biological) therapy
Find out about treating breast cancer.