Find out more about how breast cancer size, growth and spread are described.

Staging and grading

Staging and grading are ways in which healthcare professionals describe the size of your breast cancer, whether and how far it has spread, and how fast it may grow (or how ‘aggressive’ it is).

Knowing your cancer’s stage and/or grade helps your breast care team plan the best treatment for you. Staging and grading usually happens after your breast tumour has been removed by surgery, as a pathologist will need to test the tissue in a laboratory and examine it under a microscope.


The grade of a tumour indicates what the cells look like and gives an idea of how quickly the cancer may grow and spread. Tumours are graded between 1 and 3.

Grade 1 – the cancer cells look small and uniform like normal cells, and are usually slow-growing compared to other grades of breast cancer

Grade 2 – the cancer cells are slightly bigger than normal cells, varying in shape and are growing faster than normal cells

Grade 3 – the cancer cells look different to normal cells, and are usually faster-growing than normal cells

Diagram of Grade 1, Grade 2 and Grade 3 breast cancer cells

Grading for non-invasive breast cancers such as ductal carcinoma in situ (DCIS) is different, and is defined as low, medium or high grade rather than 1, 2, or 3.


Staging is used to assess the size of a tumour, whether it has spread and how far it has spread. Understanding the stage of the cancer helps doctors to predict the likely outcome and design a treatment plan for individual patients.

The main method used for defining the stage of a cancer is the TNM (tumour, nodes, metastasis) system. The TNM system is often used to categorise cancers into four stages.

Stage 1 usually means that a cancer is relatively small and contained within the breast.

Stage 1 breast cancer diagram showing lymph nodes above breast and armpit, tumour in breast and lobe.

Stage 2 usually means the cancer has not started to spread into surrounding tissue but the tumour is larger than in Stage 1. Sometimes Stage 2 means that cancer cells have spread into lymph nodes close to the tumour.

Stage 2 breast cancer diagram showing a larger tumour but one that has not spread into the surrounding tumour.

Stage 3 usually means the cancer is larger. It may have started to spread into surrounding tissues and there are cancer cells in the lymph nodes in the area.

Stage 3 breast cancer diagram showing a tumour which has spread and cancer cells in the lymph nodes.

Stage 4 means the cancer has spread from where it started to another body organ. This is also called secondary or metastatic cancer.

Stage 4 breast cancer diagram showing a tumour that has spread to the lung

More information

More information about staging and grading can be found on the Cancer Research UK website

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Breast Cancer Now’s health information is produced following best practice guidelines developed by the Patient Information Forum. 

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