Cancer staging explained

What is cancer staging?

Cancer staging describes the size of a cancer and how far it has grown in the body.

Doctors will carry out tests to find out:

• the size of the cancer
• whether it has reached nearby tissues
• whether it has spread elsewhere in the body

Your doctor will let you know what tests you need and when your results will be available. The exact tests depend on the cancer type and may include:

• blood tests
• biopsies, which can include surgery to remove a tumour for testing
• scans (such as MRI, PET, CT)

Tests can also find out the grade of the cancer. This describes how abnormal the cancer cells are compared to normal cells. A higher-grade cancer would be likely to grow and spread more quickly than low grade.

Why is cancer staging important?

Knowing what stage of cancer you have is important to make sure you receive the right treatment. If the cancer is in one place, then treatment may be local to where it is in your body. This might include surgery or radiotherapy.

If your cancer has spread, you may need treatment throughout the whole body (systemic treatments). These can include:

• chemotherapy
• hormone therapy
• immunotherapy
• targeted therapy

Treatments can also be used in combination.

Your doctor will explain any test results to you and tell you what they mean. They’ll also discuss the possible treatment options with you. They’ll make sure you have all the information you need before you make an informed decision.

What are the different stages of cancer?

Cancer is normally staged using numbers one to four. Letters can also be used to describe the cancer’s size and spread.

The stages can be different for different types of cancer. Your doctor or specialist nurse will explain the staging system used for your cancer and answer any questions you might have.

Number staging

For cancer types that use the number staging system, there are usually three or four stages.

This is what each stage normally means.

• Stage 1. A small, early cancer that has not yet spread to anywhere else in the body.
• Stage 2. A larger tumour (cancer) than in stage 1 but is still contained to one area of the body.
• Stage 3. The cancer is larger and may have spread into surrounding tissues or lymph nodes (small lumps of tissue that trap germs).
• Stage 4. The cancer has spread to another part of the body, such as the liver or lung. This is also known as secondary or metastatic cancer.

TNM staging

The TNM (Tumour, Node and Metastases) staging system is used for many types of cancer.

• T describes the size of the tumour. The letter ‘T’ will normally be followed by a number between 1 and 4. T1 is a small tumour, and T4 is a more advanced cancer.
• N describes whether the cancer has spread to the lymph nodes. ‘N’ is followed by a number between 0 and 3. N0 means there are no cancer cells in the lymph nodes. N3 means more lymph nodes are affected.
• M describes whether the cancer has spread to other parts of the body. ‘M’ is followed by the number 0 or 1. M0 means the cancer hasn’t spread to another area, and M1 means it has.

There is also a term sometimes known as ‘stage 0’ cancer, called carcinoma in situ. This is when a group of abnormal cells are found that may develop into cancer in the future, although this isn’t always the case.

Blood cancers don’t behave like solid tumours. Doctors use different staging and grading systems to guide treatment.

Cancer staging might seem confusing initially. Don’t be afraid to ask your cancer doctor or nurse as many questions as you need to help understand your diagnosis and proposed treatment plan.

You can also reach out to charities such as Macmillan UK for support.