After diagnosing a patient with tongue cancer, a doctor will need to determine what type of cancer it is, the grade of the tumor, and the stage of the cancer. Doctors often establish a preliminary disease stage based on physical exam as well as findings on imaging that help to identify the spread of disease. In patients who undergo surgery, a more well-defined disease stage is determined based on pathology after surgery. It is important to note that oral cancers can sometimes be difficult to diagnose. If a doctor is having a hard time determining what type of cancer it is, he or she might ask for a second opinion and send some pieces of the tumor off to a specialist in head and neck pathology who deals more frequently with these types of tumors.
Type
The most common type of tongue cancer is squamous cell carcinoma. More than 90% of mouth cancers are squamous cell carcinoma. Squamous cell carcinoma is a cancer that starts from abnormal cells on the surface layer of the lips or the lining of the mouth. If the cancer is discovered at an early stage, before invading past the deepest layer of the mouth lining, then it is called carcinoma in situ and has a good prognosis when removed. Another subtype is called verrucous carcinoma. This subtype usually has a slow growth pattern and is less likely to spread to lymph nodes in the neck or other parts of the body.
Less common types of tongue cancer
| Cancer Type | Description |
|---|---|
| Carcinoma in situ (also called severe dysplasia) | This cancer is an early stage of squamous cell carcinoma in which there are cancerous cells on the lining of the mouth but they have not invaded past the outermost layer of tissue. |
| Verrucous carcinoma | This is a type of squamous cell carcinoma that has a better prognosis because it is less likely to spread. |
| Salivary gland cancers | There are minor salivary glands located under the lining of the mouth. This is why cancers in this region can be glandular malignancies referred to as adenocarcinomas, including mucoepidermoid carcinomas, and adenoid cystic carcinomas. |
| Lymphoma | The mouth also has lymphoid cells under the surface. This is why lymphoma could in rare cases appear as a lump in the mouth. |
| Mucosal melanoma | These cancers come from skin cells (melanocytes). In rare cases, melanoma can be found in the lining of the mouth, nose and/or throat. |
Grade
A doctor will rely on final pathology of the tumor to determine the grade and stage of the cancer. The grade is usually only determined after the tumor has been removed. The grade of cancer relates to how healthy or unhealthy cells look under a microscope. In other words, a pathologist will determine the grade of cancer by comparing the amount of the healthy-looking tissue to the amount of cancerous tissue. If most of the tumor cells look like normal tissue then the cancer is “well differentiated” or “low-grade.” However, if the tumor cells look very different from normal tissue then the cancer is “poorly differentiated” or “high-grade.” The grade of cancer may help to determine how quickly the cancer is likely to spread.
Oral cancer grading is described as the following:
| Grade | Definition |
|---|---|
| GX | The grade cannot be evaluated. |
| G1 | The cells look more like normal tissue and are well differentiated. |
| G2 | The cells are only moderately differentiated. |
| G3 and G4 | The cells don’t look like normal tissue and are poorly differentiated. |
Stage
The stage of a cancer is determined by the TNM staging system:
- The ‘T’ stands for tumor size.
- The ‘N’ stands for lymph node involvement.
- The ‘M’ stands for distant metastases, or cancer spread to other areas of the body.
Staging helps doctors determine how serious the cancer is and how best to treat it. Staging systems often reference very specific anatomical structures. Please reference the anatomy page to learn more about these terms.
Staging is generally based on the American Joint Committee on Cancer (AJCC) 8th edition guidelines. To learn more, see the AJCC TNM Staging Table and the TNM Staging Tool below.
TNM Staging Table, from the American Joint Committee on Cancer (AJCC)
| T | N | M | Stage |
| T1 | N0 | M0 | I |
| T2 | N0 | M0 | II |
| T3 | N0 | M0 | III |
| T1,2,3 | N1 | M0 | III |
| T4a | N0,1 | M0 | IVA |
| T1,2,3,4a | N2 | M0 | IVA |
| Any T | N3 | M0 | IVB |
| T4b | Any N | M0 | IVB |
| Any T | Any N | M1 | IVC |
