What is staging?

Once your doctor has made a diagnosis of cancer, it is important that they assess the extent (or stage) of the cancer. Staging a cancer is important because it helps doctors to choose the best treatment for you. It also gives information about the chances of cure.

The TNM (Tumour, Node, Metastases) system is used to stage cancer. This system is used to summarise information about the size of the cancer and whether it has spread to lymph nodes at other parts of the body.                                                                                                                               

T T stands for the size of the cancer. For cancer of unknown primary, the letter ‘x’ is used (Tx) instead of a number.
N N indicates the size and number of lymph nodes involved by the cancer. An N value for cancer of unknown primary can range from 1 to 3, depending on the size and number of cancerous lymph nodes. 
M M stands for distant metastases, or whether the cancer has spread to other parts of the body outside the head and neck. An M value can be either 0 (cancer has not spread to other parts of the body) or 1 (cancer has spread to other parts of the body).
Once the values for T, N and M have been worked out, they are combined to give an overall score between 1 and 4.
Your doctor may write this in Roman numerals: I, II, III and IV.

Staging is complicated but in broad terms cancers may be described as:

  • Early stage cancer (Stage I or II cancers), which are small (less than 4 cm) and have not spread. This does not apply to cancer of unknown primary because by definition they have spread.

  • Advanced stage cancer (Stage III or IV cancers), which are more advanced due to their size (more than 4 cm) have spread to nearby parts of the body, the lymph nodes, or other parts of the body. All cancers of unknown primary are stage III or IV.

The chance of cure depends on both the type  of cancer and the stage. It is important to know that most patients with cancer of unknown primary (even stage III or IV) can be cured. 

What is grading?

Your doctor may also be interested in the grade of the cancer. Grading refers to the growth pattern of the cancer. The grade of the cancer is determined by a pathologist who examines a biopsy sample under a microscope. The pathologist determines the grade of the cancer by how the cells look. The grade can be used to estimate how quickly the cancer is likely to grow and spread. Grading is usually determined by a biopsy sample of the primary cancer and therefore is not very important in cancer of unknown primary.