About stages and grades

The stage and grade of your nasal or paranasal sinus cancer help doctors to decide on the best treatment for you.

What is staging?

The stage of a cancer means how big it is and whether it has spread. It is important because the stage often decides the treatment. The tests and scans you have to diagnose cancer give some information about the stage, but your doctor may not be able to tell you the exact stage until you have surgery.

The staging systems used by doctors

There are different ways of staging cancers. The 2 main ways are the TNM system and number classification system.

You may not be familiar with these terms but you can ask your doctor if you would like to know more.

Understanding your staging may show why your doctors have chosen a particular treatment.

TNM stages

TNM stands for tumour, node and metastasis. The system describes:

  • the size of a primary tumour (T) and how far it’s grown locally
  • whether the cancer has spread to the lymph nodes (N)
  • whether the cancer has spread in the bloodstream to a different part of the body (M)

Number stages

Number staging systems use the TNM system to divide cancers into stages. Most types of cancer have 4 stages, numbered from 1 to 4. Doctors often write the stage down in Roman numerals. So they may write stage 4 as stage IV. 

There are separate number stages for cancers of the nasal cavity, maxillary sinus and ethmoid sinus. This is because each type is surrounded by different structures and tissues in the head.


Even within a single type, cancers can vary according to what the cells look like under a microscope.

Specialists called pathologists examine the cancer cells. They look at how different they are from normal cells. They classify the cells according to how abnormal they look. Doctors call this differentiation or grade.

Well differentiated cancer cells are low grade. These are most like normal cells. Poorly differentiated cancer cells are high grade and are very abnormal in appearance. Sinonasal undifferentiated carcinoma (cancer) cells are so abnormal that it is hard to tell what type of cell they originated from. This is despite extra tests to help find this out. They are therefore a type of tumour called sinonasal undifferentiated carcinoma (SNUC). 

In general, a low grade cancer is likely to grow more slowly. It is also less likely to spread than a high grade cancer.

Staging and grading of nasal cavity and paranasal sinus cancers

Cancer can develop in the nasal cavity or any of the several pairs of sinuses. The cancer may then spread to nearby tissue, the lymph nodes or other parts of the body.

The staging of nasal and paranasal sinus cancers is complex. The staging systems are only for maxillary sinus, ethmoid sinus and nasal cavity cancer.

For a cancer anywhere else in the sinuses your doctor will decide on your treatment differently. They will look at the size, location and type of the tumour you have.

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