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 stage is based on the size of the cancer, whether it has invaded into nearby areas and whether it has spread to lymph nodes in the neck (called lymph node metastases) or other sites in the body, such as the lungs, liver or bone (called distant metastases).

Some people will need more tests such as CT or PET scans to see if their skin cancer has spread, or not, and help in deciding the stage of the cancer.
Most people with a NMSC (a small BCC or SCC) do not need more tests after a biopsy. People with more advanced tumours may be advised to have some extra tests. People with an advanced NMSC, melanoma or MCC are more likely to be advised to have more tests.

The staging systems for NMSC, melanoma and MCC are all different. 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 or other parts of the body.

The TNM system
T T stands for the size of the cancer. A T value can range from 1 (small cancer) to 4 (large cancer).
N N indicates whether the cancer has spread to the lymph nodes. Where there is no cancer in the lymph nodes, the N value is 0. An N value 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 these as 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 and have not spread to the lymph glands or other parts of the body.

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

What is grading? 

Staging and grading are not the same. 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 the 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 not always important in a skin cancer diagnosis.