At some point, your doctor will tell you what stage of mouth cancer you have. Put simply, the stage describes how widespread or advanced the cancer is. Determining the stage helps doctors explain the extent of the cancer to you. It also helps them determine how to move forward with treatment, including surgery, radiation therapy, or chemotherapy.
Your doctor will assign a stage to your cancer after your physical exam and the initial results from your oral tissue biopsy or imaging tests. The stage may be adjusted if you have additional tests or after surgery. There are five stages of mouth cancer, starting at zero and going up to four. (They are represented by the Roman numerals I, II, III, and IV.)
These are the basic stages of mouth cancer:
Stage 0 is also called carcinoma in situ, and this is the very beginning of the scale. It describes abnormal cells in the lining of the lips or oral cavity, which have the potential to become cancer.
Stage I describes a very early stage of cancer. The tumor is not more than 2 centimeters, and the cancer has not reached the lymph nodes.
Stage II describes a tumor that is larger than 2 centimeters but not more than 4 centimeters. Stage II cancer has not reached the lymph nodes.
Stage III mouth cancer describes cancer that either is larger than 4 centimeters or has spread to a lymph node in the neck.
Stage IV is the most advanced stage of mouth cancer. It may be any size, but it has spread to:
- nearby tissue, such as the jaw or other parts of the oral cavity
- one large lymph node (more than 3 centimeters in size) and on the same side of the neck as the tumor, multiple lymph nodes of any size on the same side of the neck as the tumor, or one lymph node of any size on the side of the neck opposite the tumor
- distant parts of the body beyond the mouth, such as the lungs
Mouth cancer may be stage IV when it is first diagnosed. Stage IV mouth cancer can also be recurrent mouth cancer (cancer that has come back after treatment). The cancer may recur in the part of the body where it originally developed (regional recurrence), in the lymph nodes (regional relapse), or in another part of the body (called distant recurrence).
Stage III and stage IV cancers are more likely to recur than earlier-stage cancers.