I read about sinus cance in one of your questions, and I need to know what exactly sinus cancer is, what its symptoms are and who is likely to have it.

N.M.

Sinuses are "air pockets" in the bones of the face, so it is certainly reasonable to wonder how an air pocket could give rise to a cancer. The answer is very straightforward: Sinus cancers typically arise from the lining of the sinus, a tissue known as mucosa. Less commonly, the bone itself can be the source of the cancer.

Unfortunately, the symptoms of sinus cancer may be very subtle. Also unfortunate is the fact that several of the symptoms are so innocent that the patient may ignore them for a very long time.

The common, early symptoms of sinus cancer are nosebleeds (either blood-streaked nasal mucus, or recurrent "gushers"), tooth pain and a persistently obstructed (stuffy) nose. Symptoms of a more advanced sinus cancer can be understood by considering the effect a large cancer may have on adjacent tissues:

• If the cancer invades the nerve that gives sensation to the cheek, cheek numbness (or pain) will result.
  
• If the cancer presses on the tear duct, excessive tearing may result.
  
• Blurry vision and double vision result from pressure on (or invasion of) the muscles that move the eye, and the eye itself.
  
• Some large cancers may be obvious to the naked eye: There may be an asymmetric "bulge" of the cheek or nose.
  
• Sinus cancer can lead to loosening of the upper teeth or to a change in the way the teeth meet when you close your jaws.
  
• Ear "pressure" and hearing loss may occur if the sinus tumor puts pressure on the eustachian tube.
  
• Finally, if the cancer has spread (metastasized) to one of the lymph nodes in the neck, the patient may notice a lump in his or her neck.
  

Fortunately, sinus cancers are uncommon, so no one is "likely" to develop this type of cancer. There are some well known environmental risk factors, however. Sinus cancers are somewhat more common in individuals who have been exposed to wood dust, certain heavy metals (such as chromium and nickel), a variety of organic chemicals (such as the polycyclic hydrocarbons), aflatoxin (a poison produced by a fungus that grows on certain foods) and mustard gas (a weapon of war). Usually, such exposures are more common in people with certain types of jobs, but military service and recreational activities are also relevant.

As with any cancer, the treatment and prognosis of sinus cancer depends on the location of the cancer, whether adjacent tissues are involved and whether it has spread to the lymph nodes (or to other organs). Surgery and radiation therapy, usually in combination, are the most common treatments. Chemotherapy, cryotherapy (freezing the tumor with liquid nitrogen) and electrodesiccation ("frying" the tumor with electrical current) are occasionally used to treat inoperable tumors.

Chances are, if you are worried enough to ask this question, you owe it to yourself to be seen by an ear, nose and throat surgeon. Share your concerns; if you do, your ENT (ear, nose and throat doctor) will probably go out of his or her way to do whatever is necessary to reassure you.