Mouth Sores from Chemotherapy

Oral thrush is a fungal infection of the mouth often caused by an overgrowth of Candida albicans. But why do people receiving cancer treatment sometimes develop it? And, is there any way to prevent oral thrush? 

We checked in with Adegbenga Otun, D.D.S., who researches the oral microbiome. Here’s what he wants cancer patients and their caregivers to know. 

Why do some people develop oral thrush?

The oral cavity is home to many microorganisms, including bacteria and yeast. When everything stays in balance there, your mouth remains healthy.  

Unfortunately, that balance can be disrupted by many factors, including:  

• immunosuppression 
• xerostomia (dry mouth) 
• medications 
• autoimmune diseases 
• uncontrolled diabetes 
• poor oral hygiene 
• faulty dental prostheses 
• chemotherapy
• radiation therapy to the head and neck area 

Any of these may result in otherwise small and quiet organisms flourishing and causing disease.  

One of those diseases is an infection caused by yeast — or a type of fungus — called Candida. The most common species in this group is Candida albicans. Others include Candida tropicalis, Candida krusei and Candida glabrata.  

What does oral thrush look like?

 Candida infections of the oral cavity can appear in a variety of ways. But there are four basic types. 

1. White type: This is what people usually think of when they hear the word “thrush.” It’s the most common and well-known presentation. Known as pseudomembranous candidiasis or “florid” thrush, it appears as a white coating or curdish patches on the tongue and other interior surfaces of the mouth. It can usually be wiped off, leaving behind a red surface. 
   
   
2. Red type: This is less common and also known as erythematous candidiasis. The name comes from the Greek word “erythema,” which means red. In long-term denture-wearers, it’s normally seen as a stark red outline on the denture-bearing area. However, erythematous thrush can make the entire inside of the mouth look inflamed in patients who have chronic dry mouth, Sjogren's syndrome, or have received radiation therapy to the head or neck.
   
   
3. Angular cheilitis: Usually seen as redness or cracks at the corner of the mouth, this is often just an extension of a thrush infection in the oral cavity. It’s primarily seen in patients wearing old, worn-out dentures.  
   
   
4. Median rhomboid glossitis: This usually appears as a reddish patch in the middle of the back of the tongue.  

Does oral thrush hurt?

It depends on the person. Some patients report experiencing a foul taste, a bad odor or a burning sensation in their mouths, but not all do.  

Why do some cancer patients develop thrush?

Saliva is a complex fluid that’s critical to maintaining the health of the oral microbiome. So, anything that disrupts the quantity or quality produced can create a shift in disease-causing microorganisms.  

For cancer patients, that could mean long-term use of medications, such as steroids that suppress oral immune defenses, antihypertensives that make the mouth drier, or chemotherapy- or radiation therapy-induced changes to saliva quality.

The pH of the oral cavity becomes more acidic when it’s dry for long periods of time. This favors the growth of Candida. That’s why cancer patients who have had radiation therapy in the head and neck region are very susceptible to repeated Candida infections. 

How can I tell if I have thrush?

You likely have thrush if the white coating or lesion on your tongue or other surfaces of the mouth: 

• appears “curdish,” like cottage cheese, 
• can be easily wiped off, and 
• leaves a reddish erythema behind.  

If the white coating or lesion on your tongue can’t be wiped off, it’s probably something else. The only way to tell for sure is to have a doctor swab the inside of your mouth and submit it for a growth culture.   

If you have a persistently dry mouth, you may be susceptible to thrush. A well-hydrated oral cavity glistens and feels slick to the touch. But it feels sticky and looks different when it’s dry. As the tongue becomes drier, the papillae, or tiny raised projections on its surface, also may become more pronounced. The tongue can even develop cracks or fissures if it’s been dry for a long time. 

How is thrush typically treated?

We have two ways of treating thrush: topically and systemically. 

Topical treatments usually consist of antifungal oral rinses that weaken the cell walls of Candida so that they become leaky and die. Some of these rinses must be spat out after swishing, but others can be swallowed if the fungal infection extends to the back of the throat.   

There are also antifungal pills you can take to treat thrush. This option is viable when oral rinses or lozenges do not clear persistent or recurrent infections. The downside of systemic antifungals is that they have many drug interactions, which can limit their use.  

Are there any other conditions that can mimic thrush?

Yes. Several conditions can mimic oral thrush. These include: 

• frictional keratosis: a persistent, usually isolated, low-grade irritation of the oral mucosa 
• hairy leukoplakia of the tongue: commonly seen in HIV patients  
• lichen planus 
• smoker’s keratosis 

Anything else people should know about oral thrush?

Fungal infections must be managed promptly in patients who are immunocompromised during cancer treatment; these infections can be fatal.  

Is there any way to prevent thrush?

Yes. But it’s more about reducing the risk factors that can lead to it. 

• Use a baking soda mouthwash: Rinsing out your mouth a few times a day with a baking soda solution can help replicate the oral cavity’s normal alkalinity and buffer any acids. 
• Scrub your tongue: When it comes to oral hygiene, caring for your tongue is just as important as caring for your teeth. So, scrub your tongue daily with a toothbrush and use a tongue scraper at least twice a week. As a general rule, any time a brush goes into your mouth, it should also be scrubbing your tongue. 
• Consider changing medications: Some medications can affect the quantity or quality of your saliva. So, if you’re getting repeated oral thrush infections, ask your doctor about medication alternatives. 
• Get proper dental care: Every living thing produces waste that can be used by other organisms to grow. Even tooth decay can change the oral flora so that it creates a welcoming environment for something else. So, have broken or decaying teeth repaired promptly. 
• Replace dentures regularly: Just because you’re still able to wear dentures made for you 20 or 30 years ago doesn’t mean they’re working properly. Dentures are designed to be effective for about five years. So, if you’re wearing dentures older than that, look into having them replaced.  
• Take your dentures out every night: Saliva contains a lot of protective agents, but dentures prevent it from reaching and coating all the surfaces inside your mouth. So, take out your dentures every night and give your oral tissues a break. 
• Disinfect your dentures: Most dentures have a porous surface, so Candida can grow there and cause reinfection. If you develop a Candida infection, don’t forget to disinfect your dentures in a diluted bleach solution before using them again. 

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

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.