Primary breast cancer is breast cancer that hasn’t spread beyond the breast or the lymph nodes under the arm.

Breast cancer starts when cells in the breast begin to divide and grow in an abnormal way. It’s not one single disease and there are several types of breast cancer.

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.

The breasts and lymph nodes

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.

Breasts contain a network of thin tubes called lymph vessels. These are connected to the lymph nodes (glands) under the arm.

The breast and lymph nodes diagrams

Types of primary breast cancer

There are different types of breast cancer. It’s important to have an accurate diagnosis so your specialist team can plan the most appropriate treatment for you.

Breast cancer can be invasive or non-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 form of breast cancer, sometimes called intraductal, non-invasive or pre-invasive cancer.

The cancer cells are inside the milk ducts (‘in situ’). If it’s 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 that it has or will spread, and treatment aims to reduce the risk of this happening.

Invasive ductal breast cancer (of no special type)

Invasive ductal breast cancer is the most common type of breast cancer. It’s also called breast cancer of no special type (NST) or not otherwise specified (NOS).

Breast cancer started in the milk ducts and has spread into the surrounding breast tissue.

Other types of breast cancer

Other types of breast cancer are known as special type. When these cancer cells are looked at under a microscope, they have distinct features that identify them as a particular type. These include:

There are several other rare special types of breast cancer. These include:

Treatment for primary breast cancer

Treatment for primary breast cancer can include:

  • surgery
  • chemotherapy
  • radiotherapy
  • hormone therapy
  • targeted (biological) therapy
  • bisphosphonates.

Find out about treating breast cancer.

Last reviewed: August 2016
Next planned review begins shortly

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