The mouth feels dry and sticky – not only athletes or people with stage fright experience this. Many cancer patients are also affected. The causes are varied: sometimes it's just an acute lack of fluids, for example after an operation. Sometimes it is cancer drugs or other medications that lead to temporary dry mouth. In the seriously ill, nutritional problems, lack of thirst or problems with breathing can dry out the mouth. Permanent dry mouth can occur after radiation treatment or surgery for cancer of the mouth or throat. The reason: the salivary glands are damaged by radiation or removed during surgery.
Dry mouth? Almost everyone is familiar with this: when experiencing stage fright or stress, emotional upheaval and excitement, you sometimes “run out of breath”. For cancer patients, however, prolonged dry mouth can become a real burden, for example if dry mouth occurs as a side effect of some medications, or if the salivary glands themselves are permanently damaged.
What is missing in a dry mouth is saliva. It is largely formed in the six large salivary glands: the two parotid glands, the two mandibular salivary glands and the two sublingual glands. A large number of smaller salivary glands are located in the lips, palate, cheeks and tongue. In total, the salivary glands produce about 0.5 to 1.5 liters of saliva per day. Saliva consists of 99 percent water, but also some substances dissolved in it.
But what is saliva good for anyway?
It moistens the sensitive mucous membranes of the mouth.
It makes food slippery and makes it easier to swallow.
It contains enzymes that break down the starch in food into small pieces in the mouth.
It makes the sensation of taste possible.
It protects and cleans the oral cavity – special proteins in saliva prevent the multiplication of pathogens.
It protects teeth – the fluoride it contains regenerates tooth enamel. Acids, for example from fruit, are neutralized by saliva.
It makes the lips and tongue flexible and thus enables speech.
If there is too little saliva over a longer period of time, experts speak of xerostomia. Doctors consider this to be a serious medical problem: Those affected are prone to infections of the oral mucosa. Damage to the teeth is also possible. Speaking, chewing and swallowing can also cause problems. And in many patients, the sense of taste suffers.
When can dry mouth occur in cancer patients?
Lack of fluids: An important trigger is simply lack of fluids. Dry mouth is possible around an operation, for example, when people are not allowed to drink anything because of the anesthesia. Older people in particular often lack the feeling of thirst and therefore drink too little. If you suffer from fever or nausea during a cancer illness or treatment, this also dries out your mouth. In most cases, the symptoms improve once the lack of fluids has been compensated for.
Medications: Some cancer drugs or other medications can lead to temporary dry mouth as a direct side effect because they slow down saliva production. Here, too, the problem recedes at the latest when the medication is discontinued.
Radiation or surgery of the salivary glands: Quite a few people who have been treated for a head and neck tumor suffer from long-term or even permanent dry mouth. This mainly includes cancer of the mouth, tongue, throat or larynx. Radiation or surgery can damage salivary glands.
Advanced disease: persistent dry mouth also affects many people with advanced cancer: This is especially true when eating and drinking are problematic, when affected individuals require high doses of pain medication, or when breathing is difficult.
Non-cancer-related causes: Finally, cancer patients may also suffer from concomitant diseases that – independent of their tumor disease – lead to dry mouth.
If a constantly dry mouth causes problems, you should contact your doctors. They can check what the possible causes are and what can be done about it. Otherwise, the following applies to all forms of dry mouth: You should drink enough, preferably water, and always moisten your mouth sufficiently. Good oral and dental care is also important. Experts recommend regular visits to the dentist.
Does dry mouth last longer, for example because the salivary glands have been damaged by radiation therapy or surgery?
As long as there is still some residual function, stimulating measures can be considered, from chewing sugar-free gum to medication. If this doesn't work at all and the mouth remains dry, “artificial saliva” can help: The attending physicians can advise which products are suitable as medicines or medical devices.
In the case of seriously ill patients, good oral care is particularly important: help with drinking and oral care and, if necessary, regular moistening of the mouth.
Some forms of cancer treatment or the cancer itself cause some patients to feel thirsty, sweat more, have a fever, diarrhea or vomit. They lose a lot of fluid, which also dries out the oral mucosa.
The most important measure is to compensate for the lack of fluid and, if necessary, to keep moistening the mouth. Seriously ill and many elderly people require appropriate nursing assistance.
Some cancer drugs as well as drugs for pain, nausea, depression, high blood pressure, allergies or asthma can dry out the mouth as a side effect. In this case, lack of fluid is not the main cause: this side effect is rather caused by the regulation of saliva production.
One should not independently discontinue medications due to this side effect, but always discuss this with the treating physicians. They can check whether the respective preparations can be replaced by others that do not affect saliva production.
Long-term dry mouth: How does head radiation affect the salivary glands?
Patients with thyroid cancer undergoing radioiodine therapy can also have their oral and parotid glands affected or destroyed. Patients with tumors in the mouth, throat and neck are particularly affected with radiation therapy. Finally, patients who have some or all of their salivary glands removed because of a tumor also suffer from more or less pronounced dry mouth.
Dry mouth can only be expected if one or more glands are directly affected by the treatment. Whether symptoms occur and how pronounced the dry mouth is depends on how many and which salivary glands are located in the radiation area and how high the radiation dose is, or how many glands had to be surgically removed.
One piece of good news is that modern radiation techniques mean that dry mouth is no longer as likely to occur in patients with head and neck tumors, nor is it as pronounced in most sufferers as it used to be. Radiation can now be directed much more specifically to the affected tissue: The tissue of at least part or even all of the salivary glands is thus spared.
What happens if the salivary glands nevertheless fail completely?
When saliva production is completely absent, affected individuals describe that their mouth feels dry and sticky, their tongue burns, and their mouth hurts. Simply drinking more is not enough in the long run: Without saliva, chewing, swallowing and sometimes even speaking become difficult. Bad breath can become a problem and the sense of taste suffers.
In the long term, inflammation and infection of the oral mucosa and caries can occur. Anyone who has an extremely dry mouth over a long period of time loses quality of life: without further treatment, the extremely dry mouth can hurt and prevent sufferers from sleeping.
Even if salivary flow has only been reduced by cancer therapy, dry mouth should not simply be resigned to: Good treatment adapted to the personal situation prevents long-term consequential damage.
Oral and dental care
Reduced saliva flow increases the risk of inflammation and infection of the oral mucosa and adjacent tissues. The first sign is often bad breath. The teeth can also be affected. Experts therefore advise good oral and dental care to protect the oral cavity from infections and the teeth from caries.
Most patients with very advanced cancer suffer from pronounced dry mouth – a symptom that is often felt to be particularly distressing. Food intake, taste experience and speaking are severely impaired as a result – all things that make up a good quality of life.
Good and regular oral care or oral moistening is therefore very important for affected patients. Many seriously ill patients need support from relatives or nurses. Because: In this phase of life, strength and flexibility are not always enough to take this into your own hands or even to express the problem.
The attending physicians or nurses can provide guidance and recommend appropriate products to clean the teeth, gums and mucous membranes thoroughly, yet gently.
To keep an eye on the condition of the teeth, specialists also recommend regular visits to the dentist. He or she can help if problems arise with severe xerostomia, such as mucosal or gum disease. Dentists are also the right people to contact if dry mouth makes dentures feel uncomfortable or no longer fit.