Dry mouth (xerostomia) in cancer patients: 5 things to know

Xerostomia is the scientific term for a chronically dry mouth. Though it might not seem like that big of a deal, dry mouth is actually a very uncomfortable — and potentially serious — side effect of cancer treatment. 

But what causes dry mouth in cancer patients? How is it treated? And, can you prevent xerostomia?

We went to oral oncologist Mark Chambers, D.M.D., for answers. 

What are the main causes of dry mouth?

Among cancer patients, xerostomia is primarily caused by radiation therapy to the head and neck or surgical removal of the salivary glands. But many other factors can contribute to this condition. 

Some of the main causes of dry mouth are:

• immunotherapy agents
• chemotherapy drugs
• antihistamines
• pain medications
• hypertension drugs
• steroids
• stress
• diabetes
• vitamin deficiencies
• excessive salt intake
• autoimmune disorders, such as scleroderma and Sjögren’s syndrome

When I surveyed cancer patients to identify the five most-problematic side effects in 2000, dry mouth was among the most common. 

Are any treatments available for dry mouth? 

Yes. But if your salivary glands have been damaged or removed, we can only treat the symptoms. We can’t fix the underlying problem. There are some medications that treat dry mouth, but when you stop taking them, you lose the extra function. 

Fortunately, the remaining salivary glands tend to compensate for any that are damaged or missing. That’s why one of the first things we do is analyze a patient’s diet and habits. Our goal is to identify simple lifestyle solutions that might help patients first, before moving on to more complex or drug-based therapies.

Table salt, for instance, can dry your mouth out. Soy sauce does, too. So, “saltaholic” patients who use those products frequently might be asked to consider lifestyle changes that would bring them some relief.

Soft drinks can also cause dry mouth. Some people think that these beverages stimulate saliva production. Actually, the opposite is true. The acidity, carbonation, sugar and added extracts in colas in particular combine to create a film that can plug some of the minor salivary glands inside the mouth. So, we encourage patients to drink more water instead. Staying well-hydrated is very important.

That being said, once we’ve exhausted all possible lifestyle changes, we can try:

• sialagogues, which are FDA-approved drugs that stimulate saliva production
• prescription fluoride agents to maintain optimal oral hygiene 
• antimicrobials to prevent dental caries and oral infections, and 
• saliva substitutes to relieve dryness.

Other, non-traditional approaches for treating xerostomia include: 

• acupuncture 
• transcutaneous electrical nerve stimulation (TENS), and 
• gene therapy.

Sugar-free chewing gum and lozenges containing xylitol may also help alleviate xerostomia. 

How does artificial saliva work?

Saliva replacements are topical agents that come in either gel or liquid form. They can be sprayed or squeezed into the mouth. Each contains various ingredients designed to lubricate the oral cavity. There are about 30 different varieties available.

It’s important to note that while these products may provide some temporary relief, they won’t resolve the underlying issue. They’re still a good option for patients who might not want to drink too much water, though. They’re easy to use and easy to carry.

Can dry mouth be prevented?

Almost all patients who undergo radiation therapy of the head and neck area will have some degree of xerostomia as a result of damage to their salivary glands. 

But cancer patients can reduce their risk of dry mouth due to other factors by avoiding certain food items, including:

• caffeine
• soy products
• alcohol

Alcohol and phenol-containing mouthwashes also are known to increase xerostomia during treatment, so you can reduce your risk of dry mouth by avoiding these, too.

We’re investigating several parotid-sparing techniques in radiation therapy right now as well. If we can reduce the amount of damage caused to our patients’ salivary glands without affecting the results of their treatments, that would be very beneficial.

Why is it important to address dry mouth quickly? 

Saliva is a complex bodily fluid that helps people taste, chew, swallow and digest their food. It also helps them speak more easily and maintains the delicate balance of flora in the oral cavity. The major salivary glands combined produce up to 1.5 liters — or more than six cups — of saliva each day. This accounts for up to 90% of our salivary secretions.

So, when something happens to disrupt that flow, it’s a problem. With a chronically dry mouth, the microbiome in the oral cavity changes markedly. This can cause harmful bacteria to increase substantially, and lead to tooth decay, oral infections like thrush, bone infections, and even jaw fractures in the worst cases. Some of these conditions may be more challenging than the cancer treatment itself. And, they can be devastating if they’re not caught soon enough.

Early digestion starts in the oral cavity, too, so when you have minimal to no saliva, you also start seeing more issues like acid reflux. 

A substantial number of our patients also wear some type of oral prosthesis. When one of them has xerostomia, it can be very challenging and uncomfortable. We try to give our patients the best possible quality of life after cancer treatment. So, if someone is experiencing xerostomia, it needs to be addressed quickly.

Request an appointment at MD Anderson online or by calling 1-877-632-6789.