The paranasal sinuses consist of: the frontal sinuses – located above the nose; the ethmoid sinuses – located just behind either side of the upper nose; the sphenoid sinuses – located behind the ethmoid sinus in the center of the skull; and the maxillary sinuses – located under the eyes and in the upper part of either side of the upper jawbone. Cancerous lesions of the maxillary sinuses are twice as common as those of the nasal cavity. Risk factors associated with the development of nasal and paranasal sinus tumors include exposure to nickel, chromium, mustard gas, isopropyl alcohol and radium; thoratrast (a contrast agent once used in x-ray procedures) and possibly chronic sinusitis also have been linked with development of paranasal sinus tumors. The most common type of tumor in these regions is squamous cell carcinoma. Squamous cells are thin, flat cells resembling fish scales. They are found in the tissue that forms the surface of the skin, the lining of the hollow organs of the body, and the passages of the respiratory and digestive tracts. Commonly these tumors are well defined and slow growing, with a low tendency to spread (metastasize) either locally, regionally or distantly.
Staging
Particular tumor stages for the nasal cavity and paranasal sinuses are as follows: TX: Primary tumor cannot be assessed. T0: No existence of primary tumor. Tis: Carcinoma in situ (early cancer that has not spread to neighboring tissues). T1: Tumor limited to antral mucosa with no erosion or destruction of bone. T2: Tumor with erosion of the infrastructure including the hard palate and/or middle nasal meatus. T3: Tumor invades any of the following: skin of cheek, posterior wall of maxillary sinus, floor or medial wall of orbit, anterior ethmoid sinus. T4: Tumor invades orbital contents and/or any of the following: cribriform plate, posterior ethmoid or sphenoid sinuses, nasopharynx, soft palate, temporal fossae, pterygomaxillary fossae or skull base.
Treatment
Primary therapy is surgical resection (removal) of the tumor, although with early lesions surgery and radiation treatment yield approximately equivalent results. Because early stage tumors present a low risk for spreading to the lymph nodes, elective treatment of the regional lymph nodes (in the neck) usually is unnecessary. Most advanced tumors (T3 or T4) are treated with a combination of surgery and postoperative radiation treatment. Maxillary sinus cancers are treated with surgery and postoperative radiation. Surgical excision may be impractical if the cancer extends to the base of the skull, the nasopharynx or the sphenoid sinus. In such cases radiation alone may be used, although in the long run, its ability to prevent the cancer from spreading is poor. There is some data to suggest that combining chemotherapy (either intra-arterial or intravenous) with radiation may improve local control. The most commonly used chemotherapy agents are Cisplatin (an anti-cancer drug of the type called platinum compounds) and/or 5-FU, although newer agents are being tested.