Staging and grading

The stage of a cancer describes its size and if it has spread from where it started. This information affects the decisions you and your doctor make about your treatment. They won’t know the exact stage of the cancer until after your operation and any scans you may have had.

TNM staging

The TNM staging system gives the complete stage of the cancer:

  • T describes the size of the tumour.
  • N describes whether the cancer has spread to the lymph nodes and which nodes are involved. For example, N0 is no lymph nodes affected. N1 means there are cancer cells in 1–3 of the lymph nodes.
  • M describes if the cancer has spread to another part of the body. For example, M0 means the cancer has not spread (metastasised) to other parts of the body.

The number stage

Breast cancer can also be divided into four number stages. We have put these into a table, which you can download, to make them easier to understand.

This information is about stage 1 to 3 breast cancer. If you have stage 4 breast cancer, you may find our information about secondary breast cancer helpful.


The grade of a cancer gives an idea of how quickly it might grow. The grade is decided based on what the cancer cells look like under a microscope compared with normal cells. Knowing the grade helps your doctor decide which other treatments you need after surgery.

Grade 1

The cancer cells look similar to normal cells (are well differentiated) and usually grow slowly. The cancer cells are less likely to spread.

Grade 2

The cancer cells look more abnormal and grow slightly faster than grade 1 cells.

Grade 3

The cancer cells look very different from normal cells (are poorly differentiated) and may grow faster than grade 1 or 2 cells.

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Just been diagnosed?

Just been diagnosed with cancer? We're here for you every step of the way. There are many ways we can help.

Treatment overview

Women usually have surgery to remove the cancer – you may also have other treatments to reduce the risk of it coming back.