The physician determines the stage of the cancer based on the tumor's size and location, the size and number of lymph nodes affected and how much it has spread to distant parts of the body. Stage I is the mildest form of the disease, while stage IV is the worst form. Staging is important because it helps doctors develop the best treatment plan.
A large lymph node in the neck may be either easily seen and felt or hard to discover. In diagnosing the disease, doctors have several options, including:
- Examining the ears, nose, pharynx, larynx, tonsils, base of the tongue and thyroid and salivary glands
- X-rays and computed tomography (CT) scans of various areas of the head and neck
- Biopsy. The whole mass is usually removed, rather than taking only a small tissue sample. It is examined under the microscope to see if cancer is present.
Staging usually occurs before cancer treatment is decided. The staging system helps the surgeon to decide the prognosis and to select the best treatment plan for each individual patient.
To stage a cancer, a pathologist examines the tumor cells under a microscope and describes the cells. A computed tomography (CT) scan, magnetic resonance imaging (MRI) or positron emission tomography (PET) scan helps determine if the tumor has spread to the lymph nodes or other organs. The pathology description, and the result of the scans, helps the doctor determine the stage.
The American Joint Committee for Cancer and the International Union Against Cancer have agreed on a method to describe the stage of a cancer. This is called the TNM system:
- T is for tumor
- N is for node
- M is for metastasis (has spread to other organs)
A number from 0-4 is assigned to each letter, such as T1 N1 M0. The number describes the size of the tumor: 0 is the smallest size and 4 is the largest.
Some N (node) categories have sub-categories that use the small case letters a, b, or c. Small case letters describe the extension of cancer:
- 'A' means cancer is in the lymph nodes
- 'B' means cancer is on one side only
- 'C' means cancer is on both sides
A sub-category tumor stage might be described as T2 N2a M0.
TNM is confusing. It is not necessary to know the exact meaning of each letter and number, but a basic knowledge is helpful.
Your doctor will explain the stage of the tumor and the best treatment for you.