What to know about the stages of cancer

If you or someone you love has recently received a cancer diagnosis, your head is likely spinning with questions. Among the medical jargon and test results, you’ll probably hear about staging.  

While cancer staging can sound complicated, it’s how medical teams describe the extent of the disease — that is, how much (and where) the cancer is in your body. Here’s a look at how the process works, what those numbers mean and how doctors use this information to guide care.

Why staging matters

There are several stages of cancer, and several reasons why doctors spend time staging a carcinoma before beginning treatment. Staging provides a common language for your medical team. It helps your oncologist:

• Determine which treatments might be most effective
• Identify clinical trials for which you might be eligible
• Predict the potential course of your illness

Without staging, it’s difficult for your medical team to create a personalized care plan.  

The TNM staging system

Most doctors use a specific shorthand, called the TNM staging system, to categorize the stages of cancer. TNM breaks down the three key factors of a tumor:

• T for Tumor. This letter describes the original tumor and whether it has grown into nearby tissues.
• N for Node. This letter indicates whether the cancer has spread to nearby lymph nodes, small, bean-shaped organs that help fight infection.
• M for Metastasis. This letter identifies cancer that has spread to distant parts of the body, like the lungs, liver or bones. 

How many stages of cancer are there?

While every diagnosis is unique, medical teams typically group most cancers into five main categories, ranging from zero to four.

• Stage 0: Often called “in situ,” it means the cancer hasn’t spread to nearby tissue.
• Stage I: The cancer is relatively small and hasn’t spread deep into nearby tissues or lymph nodes; sometimes called early-stage cancer.
• Stage II: The tumor is larger and may have spread to nearby lymph nodes.
• Stage III: The tumor has grown more deeply into surrounding tissue and potentially also spread to nearby lymph nodes.
• Stage IV: Cancers classified at this stage are advanced or metastatic and have spread to other organs or distant parts of the body. 

Staging of cancer

If your oncologist mentions a letter after your stage number, like Stage IIA or IIIB, they’re providing a more granular description of the diagnosis. The number tells you how far the cancer has traveled; the letter gives you a clue about its behavior and specific characteristics.

These letters indicate a scale of intensity. Generally speaking, an A suggests the cancer is less aggressive or slightly smaller within that specific stage. As you move through B through D, oncologists consider the cancer as more aggressive or advanced. These nuances help doctors develop the best treatment plan for you based on national guidelines and their expertise.

The grading difference

It’s easy to confuse staging with grading, but each measures something different. While the TNM staging system describes a tumor’s location and size, grading refers to the cells themselves.

Low-grade cells resemble healthy cells and tend to grow slowly. High-grade cells look disorganized; they’re more likely to grow and spread quickly. The medical team will consider a cancer’s stage and grade to capture the full picture of what’s happening.  

How doctors find the stages of cancer

To get an accurate stage, your care team may suggest several different tests. You might undergo:

• Biopsies. Doctors examine cells from a small tissue sample under a microscope.
• Imaging tests. These include X-rays, CT scans, MRIs or PET scans to see inside your body.
• Lab tests. Blood or urine tests can look for markers or chemicals produced by certain cancers.
• Physical exams. A check-up can allow your doctor to feel for lumps or abnormalities. 

Moving forward with clarity

Even though researchers have made tremendous strides in cancer treatment, a cancer diagnosis is still scary. The staging numbers are part of the common language your cancer team will speak as they guide you through your treatment and help you decide on the steps for your care.