Determining if your tumor has spread — and if so, how much it has spread — is known as staging. The lower the number, the less the cancer has spread. Although each person’s cancer experience is unique, cancers in the same stages often have a similar outlook, and are treated in similar ways.
For example, the best treatment for an early-stage cancer might be surgery or radiation, while later stages may require chemotherapy, targeted drug therapy, or immunotherapy.
Staging is determined by testing, including physical exams, imaging, endoscopies (such as a colonoscopy), biopsies and sometimes surgery. It’s important to know that cancer can be staged more than once. You might get a stage when you’re first diagnosed, but often staging is updated after treatment has started. This is known as restaging.
Stages are determined by three key pieces of information:
Take a look at what the wall of the colon looks like:
The most common and useful staging is the TNM system.
In this system, the overall stage from I (one) to IV (four) is determined after the cancer is assigned a letter or number to describe the T (tumor), N (node) and M (metastasis) categories.
Confusing, right? Let’s go over it again:
When determining how much the cancer has spread, doctors first take a look at the primary tumor. This is where the cancer originated. The size, location, and growth into other areas are important to look at.
The T category is assigned a letter or a number:
Many types of cancer spread into nearby lymph nodes before they reach other parts of the body. Your doctor will check to see if cancer has spread to them.
The N category is assigned a letter or a number:
Cancer that has spread to body parts far away from the primary tumor is known as metastasis.
The M category is assigned a number:
Adding these TMN categories together can give you your stage, broadly classified into stage I, II, III, and IV.
You can use the chart below to determine which stage your cancer is:
For example, if your tumor is T3 N1 M0, you have stage III cancer.
Manju’s 7-year-old son just got back from his soccer game, and wanted to talk about his mom’s cancer.
Son: Mommy, I thought your cancer was stage IV.
Manju: No, it was stage III.
Son: What’s the difference?
Manju: My cancer was in the rectum —
Son: I KNOW! What does stage I mean? Tell me about that.
Manju: Okay… Your soccer socks have a pocket for your shin guards, right?
Son (feeling his shins): Yes, I feel 4 layers. My pants, the first layer of my sock, my shin guard, then the second layer of my sock. Then the skin of my leg. Why are you telling me this?
Manju: Wait for it. This is a very simple explanation, okay? The wall of the colon and rectum are just like your soccer uniform, they have many different layers. If the tumor is like a small rock stuck between your skin and the inner sock layer, it’s stage I. If the rock is a bit bigger, and pokes into the inner sock layer and shin guard, it’s more like stage II.
Son: And if it’s like a bigger rock, poking through the inner sock layer, the shin guard, and into the outer sock layer, that’s stage III?
Manju: Yes, you’ve got it! And stage IV is when the tumor goes through all the layers — AND can be found in some other part of the body.
Son: Like in your knee?
Manju: Like in the liver or lungs, up here.
Son: Oh, okay. So your tumor was really stage III. I get it now!
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Last updated: May 18, 2022