Dry mouth is a side effect of some cancer treatments. It may be a direct or indirect result of treatment. Saliva is necessary for taste, swallowing and speech. Therefore, a dry mouth can significantly impact daily activities and quality of life. Dry mouth treatment consists of symptomatic relief through stimulation of salivary flow, oral aids to decrease discomfort or intervention with medications.
Which treatments are likely to cause a dry mouth?
The most common therapy for cancer that causes a dry mouth is radiation therapy for head and neck cancers. The radiation damages the primary salivary glands in the mouth that generate saliva and produce a “wet” feeling, reducing their production of saliva.
Mouth sores are a side effect of many chemotherapy drugs, and this condition is sometimes called mucositis. Once you have mouth sores, you may also develop symptoms of a dry mouth. Most chemotherapy drugs can cause mouth sores, but this side effect is more frequent in patients who have been treated with the chemotherapy agents listed below:
- Alkeran® (melphalan)
- Purinethol® (mercaptopurine)
- Camptosar® (irinotecan)
- Mutamycin® (mitomycin)
- Navelbine® (vinorelbine)
- Novantrone® (mitoxantrone)
- Taxotere® (docetaxel)
- Thioguanine® (6-thioguanine)
- Velban® (vinblastine)
What are the symptoms of a dry mouth?
Symptoms of a dry mouth are:
- A small amount of thick or stringy saliva
- A sore or burning feeling (especially on the tongue)
- Changes in the surface of the tongue
- Taste changes
- Cracked lips
- Cuts or cracks at the corners of the mouth
- Changes in your ability to articulate or speak clearly
- Difficulty wearing dentures
In addition to aiding in taste, swallowing and speech, saliva is also important for protecting your teeth against tooth decay. Eating sugary foods leaves acid in your mouth, which causes minerals to be lost from your teeth, leading to tooth decay. Saliva protects your teeth by neutralizing this acid.
Because saliva is a lubricant, it also acts to protect the cells that line your mouth. Without enough lubricant, the lining of your mouth becomes more susceptible to damage. Simply brushing your teeth or eating certain foods can damage the lining of your mouth. Once you get a small cut, it may not heal normally and can develop into a mouth sore that can be very uncomfortable and may make it difficult to eat.
What is the treatment for a dry mouth?
Treatment for a dry mouth is aimed at either relieving symptoms or preventing the damage before it happens.
- Sipping water
- Gargling with a salt and soda mouthwash
- Artificial saliva spray
Pilocarpine (SalagenÒ) tablets: The drug pilocarpine stimulates salivary flow from the minor salivary glands that are known to be rich in mucin, a component of saliva that acts as a lubricant and protects the lining of the mouth and throat. Pilocarpine appears to be moderately effective in relieving symptoms of a dry mouth. In head and neck cancer patients who received radiation therapy, patients who received pilocarpine used significantly less artificial saliva, hard candy and water for relief of dry mouth symptoms compared to patients on placebo. Furthermore, the patients who received pilocarpine used significantly less artificial saliva, hard candy and water for relief of dry mouth symptoms compared to patients on placebo. In another study, pilocarpine preserved salivary function, but patients still reported difficulties with swallowing (75%), activity (80%), hyposalivation (64%), and taste (81%).
Amifostine (Ethyol®): Ethyol® is a drug that protects against the damage of radiation. Clinical trials have demonstrated that Ethyol® can reduce dry mouth and may prevent mouth sores. In patients with head and neck cancer that received radiation therapy, 51% of patients receiving Ethyol® experienced a dry mouth compared to 78% of patients receiving radiation therapy without Ethyol®. One year following completion of radiation therapy, only 35% of patients who had received Ethyol® were still experiencing symptoms of a dry mouth, whereas 57% of patients who had received radiation therapy alone were still experiencing symptoms. 
Cryotherapy (ice chips): Symptomatic relief from dry mouth can be achieved by sucking ice chips when the chemotherapy drug is most concentrated in the body. This technique, called cryotherapy, works by decreasing blood flow to the cells in the mouth, reducing exposure to the drug and decreasing the risk of developing mouth sores. Furthermore, according to a recent Cochran review, sucking ice is the only measure proven to prevent mouth sores.
What else can I do?
If you are suffering from a dry mouth, it is very important to maintain good oral hygiene in order to prevent infection or tooth decay. Try to maintain the following:
- Gently brush your teeth 2-3 times per day. Use a soft bristle brush and warm water to avoid damaging your gums.
- Rinse 4-6 times per day with a solution of salt and baking soda. Avoid mouthwashes that contain alcohol.
- Avoid foods and liquids that contain a lot of sugar. Having a dry mouth increases your susceptibility to cavities and sugar causes tooth decay.
- Drink plenty of water.
- Eat moist foods with extra sauces, gravies, butter or margarine.
- Suck on hard candy or try chewing gum.
- Eat frozen desserts (such as frozen grapes and ice pops) or ice chips.
- Use a straw to drink liquids.
 LeVeque FG, Montgomery M, Potter D, et al. A multicenter, randomized, double-blind placebo-controlled, dose-titration study of oral pilocarpine for treatment of radiation-induced xerostomia in head and neck cancer patients. J Clin Oncol 1993; 11: 1124-31.
 Fisher J, Scott C, Scarantino CW, et al. Phase III quality-of-life study results: impact on patients’ quality of life to reducing xerostomia after radiotherapy for head-and-neck cancer-RTOG 97-09. Int J Radiat Oncol Biol Phys. 2003 Jul 1;56(3):832-6.
 Clarkson JE, Worthington HV, Eden OB, et al. Prevention of Oral Mucositis or Oral Candidisis for Patients with Cancer Receiving Chemotherapy (Excluding Head and Neck Cancer). Cochrane Database Sys Rev. 2000;(2):CD000978.