In the TNM system-

The T refers to the size and extent of the main tumor. The main tumor is usually called the primary tumor

.

The N refers to the number of nearby lymph nodes that have cancer.

The M refers to whether the cancer has metastasized. This means that the cancer has spread from the primary tumor to other parts of the body.

These are all the categories for cancer staging based on TNM.

Clinical staging. Clinical staging is staging that is done before any treatment begins. Your doctor uses information from physical exams, your medical history, and any x-rays, imaging, scans, or diagnostic tests that you had. They will also use the results of any biopsy that has been done of the cancer, lymph nodes, or other tissue. Clinical staging helps you and your doctor plan the initial steps in your treatment. Clinical staging is indicated with a small "c" before the TNM category.

Pathological staging. Pathological staging is based on the same information as clinical staging, plus any new information gained during surgery if surgery was the first treatment for the cancer. Pathological staging is indicated with a small "p" before the TNM category.

Post-therapy staging. Post-therapy staging is used in cases where surgery is not the first treatment, but other treatments are given before surgery. These treatments can include radiation therapy or drug treatments like chemotherapy, immunotherapy, or hormone therapy. These treatments may be used before surgery to shrink the tumor to make surgery easier. It can also help doctors learn how well treatments work for the cancer to plan further treatment. Post-therapy staging is indicated with a "y" before the TNM category.