Nasal cavity and ethmoid sinus cancer uses the following staging scheme:

Stage 0 (Carcinoma in Situ)
In stage 0, abnormal cells are found in the innermost lining of the nasal cavity or ethmoid sinus. These abnormal cells may become cancer and spread into nearby normal tissue. Stage 0 is also called carcinoma in situ.

Stage I
In stage I, cancer has formed and is found in only one area (of either the nasal cavity or the ethmoid sinus) and may have spread into bone.

Stage II
In stage II, cancer is found in two areas (of either the nasal cavity or the ethmoid sinus) that are near each other or has spread to an area next to the sinuses. Cancer may also have spread into bone.

Stage III
In stage III, cancer has spread to any of the following:

• Eye socket
• Maxillary sinus
• Roof of the mouth
• Bone between the eyes

or

Cancer has spread to one lymph node on the same side of the neck as the cancer and the lymph node is 3 centimeters or smaller. Cancer has also spread to any of the following:

• Nasal cavity
• Ethmoid sinus
• Eye socket
• Maxillary sinus
• Roof of the mouth
• Bone between the eyes

Stage IV
Stage IV is divided into stage IVA, IVB and IVC.

Stage IVA
In stage IVA, cancer has spread to either:
One lymph node on the same side of the neck as the cancer and the lymph node is larger than 3 centimeters but not larger than 6 centimeters

More than one lymph node anywhere in the neck, and they are all 6 centimeters or smaller
and cancer has spread to any of the following:

• Nasal cavity
• Ethmoid sinus
• Eye socket
• Maxillary sinus
• Roof of the mouth
• Bone between the eyes

or

• Cancer has spread to any of the following:
• Front of the eye
• Skin of the nose or cheek
• Front parts of the skull
• Base of the skull
• Sphenoid or frontal sinuses

and cancer may have spread to one or more lymph nodes 6 centimeters or smaller, anywhere in the neck.

Stage IVB
In stage IVB, cancer has spread to any of the following:

• Back of the eye
• Brain
• Middle parts of the skull
• Nerves in the head that go to the brain
• Upper part of the throat behind the nose
• Base of the skull

and cancer may be found in one or more lymph nodes of any size, anywhere in the neck

or

Cancer is found in a lymph node larger than 6 centimeters. Cancer may also be found anywhere in or near the nasal cavity and ethmoid sinus.

Stage IVC
In stage IVC, cancer may be anywhere in or near the nasal cavity and ethmoid sinus, may have spread to lymph nodes, and has spread to organs far away from the nasal cavity and ethmoid sinus such as the lungs.

Sphenoid and frontal sinuses
There is no standard staging system for cancer of the sphenoid and frontal sinuses.