What does TNM staging mean?

TNM is the most widely used cancer staging system. According to the National Cancer Institute, most hospitals and medical centers use the TNM system as their main method for cancer reporting, and you are likely to see your cancer described this way in your pathology report.

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, meaning it has spread from the primary tumor to other parts of the body.

Numbers after each letter give more detail—for example, T1N0MX or T3N1M0. For the tumor, T1 through T4 describe increasing size or extent. For lymph nodes, N0 means no cancer in nearby nodes, and N1 through N3 describe increasing numbers of nodes with cancer. For metastasis, M0 means no spread and M1 means the cancer has spread.

Not all cancers use the TNM system. Examples that use different systems include brain and spinal cord tumors and blood cancers. A healthcare team can explain what a specific TNM stage means for a person.