Staging and grading of breast cancer

The stage of a cancer describes its size and whether it has spread beyond where it started in the body. Doctors use the results of tests and findings from surgery to decide the stage of a woman's breast cancer.

Knowing the extent of the cancer and how quickly it is likely to grow (the grade) helps the doctors to decide on the most appropriate treatment and also gives a rough idea of the outlook.

Staging

Ductal carcinoma in situ (DCIS) is sometimes described as stage 0. DCIS| is almost always completely curable with treatment.

The following stages of breast cancer are known as invasive breast cancer:

Stage 1 The tumour measures less than 2cm/1in. The lymph nodes in the armpit are not affected and there are no signs that the cancer has spread elsewhere in the body.

Stage 2 The tumour measures between 2 and 5cm/1–2in, or the lymph nodes in the armpit are affected, or both. However, there are no signs that the cancer has spread further.

Stage 3 The tumour is larger than 5cm/2in and may be attached to surrounding structures such as the muscle or skin. The lymph nodes are usually affected, but there are no signs that the cancer has spread beyond the breast or the lymph glands in the armpit.

Stage 4 The tumour is of any size, but the lymph nodes are usually affected and the cancer has spread to other parts of the body. This is secondary or metastatic breast cancer. Breast cancer that has come back after initial treatment is known as recurrent breast cancer.

This section deals with stages 1–3 breast cancer. Stage 4 is covered in our secondary breast cancer section|.

TNM staging system

Another staging system known as the TNM system is commonly used. This can give more precise information about the extent of the cancer.

• T describes the size of the tumour (cancer)
• N describes whether the cancer has spread to the lymph nodes (sometimes called glands)
• M describes whether the cancer has spread to another part of the body, such as the bone, liver or the lungs. This is known as metastatic or secondary cancer.

Grading

Grading refers to the appearance of the cancer cells under the microscope. The grade gives an idea of how quickly the cancer may develop. There are three grades: grade 1 (low-grade), grade 2 (moderate or intermediate grade) and grade 3 (high-grade).

Low-grade means that the cancer cells look very like the normal cells of the breast. They are usually slow growing and are less likely to spread.

In high-grade tumours the cells look very abnormal. They are likely to grow more quickly and are more likely to spread.

Moderate-grade or grade 2 cancers fall between these two grades and have a level of activity somewhere in between.