The short answer
The stage of a cancer describes its extent—how large the tumor is and whether it has spread. Knowing the stage helps doctors understand how serious the cancer is and plan treatment. The most widely used system is the TNM system, which describes the tumor, nearby lymph nodes, and spread.
Stage describes the extent of a cancer, such as how large the tumor is and whether it has spread.
Knowing the stage helps doctors understand how serious the cancer is, plan treatment, and find clinical trials.
The TNM system is the most widely used staging system; T is the tumor, N is nearby lymph nodes, and M is spread (metastasis).
Many cancers are also grouped into stages 0 through 4, where higher numbers mean more advanced cancer.
Watch: Cancer staging and TNM, explained
2 min 32 sec · Captioned · T, N, M and stages 0-4 — the whole staging system in plain language.
Educational only — this video explains general report language and is not medical advice. Only your care team can say what a result means for you.
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The full explanation.
The simple version
Stage refers to the extent of your cancer, such as how large the tumor is and if it has spread. Knowing the stage of your cancer helps your doctor:
- understand how serious your cancer is and your chances of survival
- plan the best treatment for you
- identify clinical trials that may be treatment options for you
The stage is a shorthand for how far the cancer has gone — and it guides many treatment decisions.
The stage stays the same
A cancer is always referred to by the stage it was given at diagnosis, even if it later gets worse or spreads. New information about how a cancer has changed over time is added to the original stage. So the stage doesn't change, even though the cancer might.
How the stage is determined
To learn the stage of your disease, your doctor may order X-rays, lab tests, and other tests or procedures. These are often the same kinds of tests used to diagnose cancer in the first place.
Most staging systems include information about:
- where the tumor is located in the body
- the size of the tumor
- whether the cancer has spread to nearby lymph nodes
- whether the cancer has spread to a different part of the body
The TNM system
There are many staging systems. Some, such as the TNM staging system, are used for many types of cancer. Others are specific to a particular type of cancer.
The TNM system is the most widely used cancer staging system, and most hospitals and medical centers use it as their main method for cancer reporting. You are likely to see your cancer described this way in your pathology report, unless there is a different staging system for your type of cancer. Examples of cancers with different staging systems include brain and spinal cord tumors and blood cancers.
In the TNM system:
- T refers to the size and extent of the main tumor, usually called the primary tumor.
- N refers to the number of nearby lymph nodes that have cancer.
- M refers to whether the cancer has metastasized—spread from the primary tumor to other parts of the body.
Numbers after each letter give more detail, such as T1N0MX or T3N1M0.
Primary tumor (T):
- TX: Main tumor cannot be measured.
- T0: Main tumor cannot be found.
- T1, T2, T3, T4: The size and/or extent of the main tumor. The higher the number, the larger the tumor or the more it has grown into nearby tissues. T's may be further divided, such as T3a and T3b.
Regional lymph nodes (N):
- NX: Cancer in nearby lymph nodes cannot be measured.
- N0: There is no cancer in nearby lymph nodes.
- N1, N2, N3: The number and location of lymph nodes with cancer. The higher the number, the more lymph nodes contain cancer.
Distant metastasis (M):
- MX: Metastasis cannot be measured.
- M0: Cancer has not spread to other parts of the body.
- M1: Cancer has spread to other parts of the body.
Stage numbers 0 to 4
For many cancers, the TNM combinations are grouped into five less-detailed stages:
- Stage 0 — Abnormal cells are present but have not spread to nearby tissue. Also called carcinoma in situ (CIS). CIS is not cancer, but it may become cancer.
- Stage I, Stage II, and Stage III (also written as Stage 1, 2, and 3) — Cancer is present. The higher the number, the larger the cancer tumor and the more it has spread into nearby tissues.
- Stage IV (also written as Stage 4) — The cancer has spread to distant parts of the body.
The higher the number, the more advanced the cancer is. Letters and numbers are often added after the first number to describe the cancer in more detail. For instance, Stage 2 prostate cancer may be further divided into 2A, 2B, or 2C.
Another way to describe stage
Another staging system, used more often by cancer registries than by doctors, groups cancer into one of five main categories. You may still hear a doctor or nurse use these terms:
- In situ — Abnormal cells are present but have not spread to nearby tissue.
- Localized — Cancer is limited to the place where it started, with no sign of spread.
- Regional — Cancer has spread to nearby lymph nodes, tissues, or organs.
- Distant — Cancer has spread to distant parts of the body.
- Unknown — There is not enough information to figure out the stage.
Whether described by TNM, a stage number, or these categories, the goal is the same: to capture how far the cancer has spread so the team can plan care.
Words to know
Tap any term to see what it means.
Common questions
What does the stage of a cancer mean?
Stage refers to the extent of your cancer, such as how large the tumor is and whether it has spread. Knowing the stage helps your doctor understand how serious the cancer is and your chances of survival, plan the best treatment, and identify clinical trials that may be options for you.
What is the TNM staging system?
The TNM system is the most widely used cancer staging system. The T refers to the size and extent of the main (primary) tumor, the N refers to the number of nearby lymph nodes that have cancer, and the M refers to whether the cancer has metastasized, or spread, to other parts of the body. Numbers after each letter give more detail.
What do the stage numbers 0 to 4 mean?
Stage 0 means abnormal cells are present but have not spread to nearby tissue (also called carcinoma in situ, which is not cancer but may become cancer). Stages I, II, and III mean cancer is present, and the higher the number, the larger the tumor and the more it has spread into nearby tissues. Stage IV means the cancer has spread to distant parts of the body.
Does the stage change if my cancer gets worse?
A cancer is always referred to by the stage it was given at diagnosis, even if it gets worse or spreads. New information about how the cancer has changed over time is added to the original stage, so the stage does not change even though the cancer might.
How is the stage determined?
To learn the stage of your disease, your doctor may order X-rays, lab tests, and other tests or procedures. Most staging systems include information about where the tumor is, its size, whether it has spread to nearby lymph nodes, and whether it has spread to a different part of the body.
Do all cancers use the TNM system?
No. The TNM system is used for many types of cancer, but some cancers have their own systems. Examples of cancers that use different staging systems include brain and spinal cord tumors and blood cancers.
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Sources last checked: 2026-07-21 what this meansLast updated: 2026-07-21Next planned review: 2027-07-21
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How this page was created
Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes. We do not employ clinicians and do not intend to — our work is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status: Source checked — This page was written with AI assistance and checked line by line against the sources listed on it. That confirms the sources support what the page says. It is not a medical review, and it does not confirm the page is complete or right for your situation.
Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.
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