By Barbara Murphy, MD

Question: “I was diagnosed with stage 4 throat cancer in May of 2000 and after the operation I could not eat and was fed through a feeding tube for 10 months. Radiation left me with no saliva. I tried a hyperbaric chamber with no results. I am very sensitive to spicy foods and cannot eat rice. I carry water with me at all times. I wear a tooth cap at night filled with fluoride paste to keep from losing my teeth. Can anything help restore saliva?”
—Sam Serra
Sequim, Washington

Answer: The salivary glands can be divided into major (parotid, submandibular and sublingual) and minor (tiny glands lining the mouth and throat). As expected, salivary glands produce saliva, which is very important for good oral health and function. Some of the critical functions of saliva include: moistening and digesting food so it can be swallowed, keeping bacteria and yeast under control, helping prevent tooth decay and lubricating the tongue and throat for speech.

Unfortunately, salivary glands are very sensitive to radiation therapy. Within a few weeks of radiation, the salivary gland function drops off quickly. Patients who have low saliva production develop dry mouth (xerostomia). The severity of dry mouth depends on how much of the salivary gland is radiated.

There are several ways of avoiding the dry mouth that occurs with radiation. This includes: 1) avoiding radiation to the salivary gland through new radiation techniques such as intensity modulated radiotherapy (IMRT); 2) use of drugs that protect from the effects of radiation such as Ethyol^® (amifostine, a drug given by vein before radiation in order to protect the salivary glands); and 3) surgically moving the major salivary glands out of the radiation therapy field. This last approach is an experimental approach being studied by investigators at the Radiation Therapy Oncology Group.

Once radiation damage has occurred, it may improve slowly over time. However, many patients never regain salivary function. Patients with dry mouth must make extra effort for oral care including: routine dental visits, regular brushing of teeth, using fluoride to prevent cavities, using chlorhexidine (Peridex^®, PerioGard^®) or hexetidine and frequent mouth rinses with baking soda or salt water.

There are several drugs that can be taken by mouth to try to increase saliva production. These include: Salagen^® (pilocarpine, one pill four times a day) or Evoxac^® (cevimeline, one pill three times a day).

Patients with dry mouth often have bothersome symptoms. The following may help diminish symptoms in some patients: artificial saliva substitutes, frequent sips of water, ice chips and lidocaine oral suspension. Patients with dry mouth often alter their diet and avoid dry, crumbly food. It is important that patients with dry mouth watch their diet to ensure what they’re eating is healthy and varied. Drinking fluids while chewing may help lubricate food so that it can be swallowed more easily.

Barbara Murphy, MD is director of the Pain and Symptom Management Program at Vanderbilt-Ingram Cancer Center in Nashville, Tennessee.