Cancer Staging

What is cancer staging?

Cancer staging is a way to measure the extent of cancer in your body. Oncologists use it for diagnosis and treatment. Cancer staging also helps researchers measure treatment patterns and outcomes. Sharing, tracking and reporting these findings helps the global medical community work together for potential cures.

It’s easy to feel intimidated by a system that describes your illness with a formula of letters and numbers. Healthcare providers understand why you might feel this way. They’ll take time to explain the cancer staging system and what it means for you.

Why do healthcare providers stage cancer?

Healthcare providers stage cancer for several reasons:

• Cancer is a complicated disease. Healthcare providers take a team approach to treating cancer. Staging systems give healthcare providers shared guidelines for diagnosing cancer and a common language to share what they’ve learned.
• Cancer treatment is evolving. The staging process gives healthcare providers a shared starting point that remains the same even as treatment options change.
• Most people who have cancer want to know what to expect, including the prognosis or expected outcome. Staging cancer gives healthcare providers a way to tap other healthcare providers’ experiences with specific cancer types and stages. Then, they use that experience to develop a prognosis.
• Staging cancer supports clinical trials and research that improves cancer treatment. Some clinical trials and research use information about people who have the same cancer type and stage. If people want to participate in a clinical trial, healthcare providers use cancer stages to identify potential trials for people to consider.

How is cancer staged?

When healthcare providers stage cancer, they focus on factors like:

• Tumor size and growth.
• Tumor location.
• Whether the cancer has spread beyond its original site.

Healthcare providers might use one or more cancer staging systems to diagnose or treat your condition. Below are some of the numbers, letters and descriptions you might see, including a summary of what they mean.

Cancer stages by size and growth

Healthcare providers use a number system to stage most cancers. The stages of cancer are:

• Stage 0 cancer: There are abnormal cells, but they haven’t spread beyond where they started. Stage 0 can also refer to pre-cancerous cells. Most stage 0 cancers are curable.
• Stage I (1) cancer: The tumor is smaller and contained to one area. It hasn’t spread to nearby lymph nodes or other areas of your body.
• Stage II (2) cancer: The tumor has grown larger and possibly spread to nearby lymph nodes.
• Stage III (3) cancer: The tumor has grown deeper into surrounding tissues and has potentially spread to nearby lymph nodes.
• Stage IV (4) cancer: Cancer has spread (metastasized) outside of the original site to other organs or distant areas of your body. This is also known as metastatic cancer.

Healthcare providers rarely use stage V (5) classification. Wilms tumor is one exception. It’s a childhood cancer that starts in the kidneys. Stage 5 Wilms tumors affect both kidneys.

What is A, B, C and D in cancer staging?

Sometimes, healthcare providers divide each numeric stage even further into categories A, B, C or D. For instance, your oncologist might say you have stage IIA (2A) or IIIB (3B) cancer. These letters offer more insight into your diagnosis.

Generally, A describes less aggressive (slower growing) cancers, while D describes more aggressive (faster growing) cancers within each numeric stage. That means a IIA cancer is less aggressive than a IIB cancer. But a IIIA cancer is more aggressive than a IIB cancer.

Cancer stages by location

Healthcare providers may also refer to cancer stage by location:

• In situ: Like stage 0 cancers, these are abnormal or cancerous cells that haven’t spread.
• Localized: There are cancer cells present, but they haven’t spread beyond the primary tumor (where cancer started).
• Regional: Cancer cells spread from the primary tumor to nearby tissues, lymph nodes or organs.
• Distant: Cancer cells spread from the primary tumor to more distant areas of your body.
• Unknown: There’s not enough information to determine the stage of cancer.

TNM staging by spread of cancer

Tumor, node, metastasis (TNM) is a common system providers use to describe the spread of cancer:

• T (primary tumor): Describes the size of the tumor and any spread into nearby tissues.
• N (node): Describes the spread of cancer to nearby lymph nodes.
• M (metastasis): Describes metastasis — the spread of cancer to other parts of your body.

TNM can stage solid tumors like breast and colon cancers, but not blood cancers like leukemia or lymphoma.

Healthcare providers may use other staging systems to diagnose some cancers. One example is the Lugano system for staging Hodgkin lymphoma and non-Hodgkin lymphoma. Another example is the FIGO system, which providers use to diagnose some cancers of the female reproductive system.

Asking your oncologist which staging system(s) they use can help you gain a fuller understanding of your cancer diagnosis.

What tests do healthcare providers use to determine cancer stage?

Healthcare providers stage cancer by doing physical examinations and tests like:

• Computed tomography (CT) scan: These scans help providers identify early-stage cancers and tumor location.
• Positron emission tomography (PET) scan: Healthcare providers may use this test to see if tumors have spread to distant areas of your body.
• Endoscopy: Providers insert a thin tube into hollow organs to examine their interior for signs of cancer.
• Biopsy: Healthcare providers obtain tissue samples they can analyze for more information about cancer.
• Blood tests for cancer: Tumor markers are substances in your blood or serum that can help providers determine tumor size or amount of cancer in your body.

Will my cancer stage change?

Contrary to what you might think, your cancer stage won’t change after your diagnosis, even if it spreads or goes into remission later.

For example, if you had stage II (2) cancer at the time of your diagnosis, you’ll always have stage II cancer. Your provider will just use additional classification terms to describe any changes:

• If it spreads to distant parts of your body, providers call it stage II cancer with metastasis — not stage IV (4) cancer.
• If treatment eliminates all signs of cancer, providers call it complete remission or NED (no evidence of disease).