Xerostomia and the Cancer Patient

Oral health is an accurate indicator of a patient’s overall health, particularly in cancer patients. In fact, a link between changes in the oral environment and radiation therapy has been recognized by the dental community since the 1930s.¹

Radiation and chemotherapy treatments to the head and neck region can permanently damage salivary glands, significantly reducing saliva production or halting it altogether. The result is temporary or permanent xerostomia, clinically defined as a subjective sensation of dryness of the mouth. Fortunately, new technology that spares more of the salivary gland tissue, like intensity-modulated radiation therapy, is becoming more widely available. Though damage to salivary glands cannot be reversed, dental professionals can assist cancer patients by recommending ways to alleviate symptoms and prevent discomfort. They can also stress the importance of maintaining optimal oral care before, during, and after treatment.

CANCER AND ORAL HEALTH

Cancer is a physically and emotionally stressful disease that creates a number of different complications. Xerostomia is one of the most common and serious health complications experienced after radiation therapy to the head and neck.² Xerostomia can impact both quality of life and long-term health, particularly when left untreated. With long-term physical health and survival the top priorities, oral health is often less important to patients. In fact, a study of patients visiting a head and neck tumor clinic found that 76% did not comply with their dental care regimen.³ This indicates that patients with upcoming chemotherapy or radiation therapy treatments need both dental care and counseling so they understand the serious effects on their oral health created by these treatments. Of more than 1 million patients diagnosed with cancer each year, as many as 400,000 may develop acute or chronic oral complications from radiation therapy to the head and mouth.⁴

A cancer patient’s severity of xerostomia is dependent on the dose and delivery of radiation therapy.² Extent of damage is determined by the dose intensity as well as the area to which radiation is delivered. Patients receiving higher doses of radiation involving all of their major salivary glands are more likely to develop the condition than those who receive lower doses to areas covering only a few glands. Mild cases result in complaints of dryness and burning sensations, while patients with a total absence of saliva experience severe burning sensations.⁵ In addition, patients who receive chemotherapy alone may experience different degrees and durations of xerostomia than those receiving radiation treatment.

CHEMOTHERAPY VS RADIATION

Both chemotherapy and radiation therapy can damage salivary glands and cause xerostomia to varying degrees. Chemotherapy patients may experience mild and temporary xerostomia, with recovery occurring 2 to 8 weeks after therapy.⁶ While the specific chemotherapeutic agents (singly or in combination) that cause xerostomia have not been clinically determined, approximately 40% of chemotherapy patients report this side effect during therapy.⁶ Patients undergoing radiation therapy, however, may experience severe and permanent xerostomia, continuing months or years after treatment. Salivary glands may not recover completely after radiation therapy ends, due to the intensity of the treatment. Radiation doses over 4,000 cGy (an abbreviation for centigray, a radiation dosage measurement) disrupt the electron orbital structure of tissue atoms, resulting in damage to individual cells and tissue.

Though some recovery of salivary function may occur following radiation treatment, patients will typically never have the same levels of saliva prior to treatment, especially if salivary glands were directly irradiated. In many cases, partial recovery is achieved when the oral cavity attempts to heal itself, with undamaged salivary glands becoming more active to offset the loss of saliva from the destroyed glands.

SYMPTOMS

Initial symptoms may cause only mild discomfort. In addition to feelings of oral dryness, patients may complain of difficulty swallowing dry food, food sticking to their teeth, or a painful burning when eating spicy foods and fruits.² Speech and taste impairment, incessant thirst, stale breath, and a sore tongue are also common symptoms.⁷ As xerostomia progressively worsens, a pebbled or fissured tongue may appear and lips may become chronically chapped.⁷ The absence of saliva can affect the tongue and gums as well, hastening the growth of yeast and other harmful fungi. Candidiasis, a disease characterized by the overgrowth of fungus on the tongue, is a common side effect of xerostomia, as is chelitis, a fungal infection that causes inflamed fissures at the corners of the mouth and white patches on mucosal surfaces.⁸ Prolonged xerostomia can result in more serious health problems, such as oral infections and dental caries.

Dental health problems can impact quality of life as well as lead to nutritional deficiencies, heart disease, bad breath, and diminished oral esthetics. In addition, chemotherapy or radiation therapy may have already weakened cancer patients’ immune systems, putting them at greater risk for oral infections to become far more serious. Dry mouth can also impact cancer patients psychologically. It negatively impacts self-esteem and is socially inhibiting, making everyday activities such as speaking and eating challenging.

DENTAL CARIES

Cancer patients who receive radiation therapy to the head and neck region are at greater risk than average for developing radiation caries—specific carious lesions associated with radiation to the head and neck area.² Caries is a major complication associated with xerostomia. Caused by decalcification of the enamel and disintegration of the dentin by acid-producing bacteria, caries is characterized by rapid decay and wearing-away of the teeth.⁷ Patients with upcoming radiation treatments should use a fluoride gel daily, prior to and during treatment, to prevent the development and progression of caries. A 5-minute daily fluoride application during radiation treatment, reduced to two or three times a week following treatment, can maintain optimal oral health and fight the development of radiation caries.⁹ Dental hygienists should apply a fluoride varnish or amorphous calcium phosphate paste after every recall appointment while the patient is undergoing treatment.

Not only does saliva prevent harmful bacteria from proliferating in the mouth, it also assists in clearing food particles from crevices within the oral cavity. When saliva is absent or not in sufficient supply, food particles can become trapped in the mouth and accelerate decay. All food particles, particularly acidic and sugary foods, will accelerate dental caries when left in contact with tooth surfaces.⁷ For this reason, patients should follow a preventive diet of bland, semisoft foods and beverages that are low in acid and sucrose.² They should also drink water frequently to rid the oral cavity of food particles.

TREATMENT

Before radiation starts, the dental hygienist needs to advise the patient and his/her medical team of any significant potential for abscess, ie, deep pockets, because this can cause severe pain during radiation therapy. Dental professionals can help cancer patients manage symptoms of xerostomia by recommending at-home treatment options designed to moisten the mouth. Patients can maintain hydration by sipping water throughout the day and using a humidifier at night. Nonacidic and noncitrus-based sugarless candy may be used to stimulate salivary flow. Drinking, smoking, and consuming spicy and acidic foods can worsen xerostomia and should be avoided.⁷ An antihistamine with coating agent is another solution, as are prescription salivary stimulants, such as pilocarpine.

Cancer patients should clean their mouths and teeth more frequently and thoroughly than average patients—at least four times per day and more if needed. In addition, routine activities such as flossing, using fluoride toothpaste when brushing, and a fluoride gel treatment should be practiced daily to maintain optimal oral health. Drug stores offer a multitude of liquid and semi-viscous saliva replacements for patients to try. The more viscous agents may be most effective for night time use. An over-the-counter oral rinse can significantly alleviate dry mouth symptoms. Oral rinses can be used along with flossing, brushing, and fluoride treatment to help manage the symptoms of xerostomia and provide relief for dry mouths symptoms.

As patients’ primary point-of-contact for oral care guidance, dental hygienists play a critical role in recommending effective treatments and stressing the importance of consistent and comprehensive oral health maintenance prior to, during, and after chemotherapy and radiation therapy. Hygienists can help cancer patients achieve the best oral care possible in a physically and emotionally stressful time by emphasizing the effect that cancer treatment can have on their long-term health.

REFERENCES

1. Del Regato JA. Dental lesions observed after roentgen therapy in cancer of the buccal cavity, pharynx or larynx. Am J Roentgenol. 1939;42:404-410.
2. Garg AK, Malo M. Manifestations and treatment of xerostomia and associated oral effects secondary to head and neck radiation therapy. J Am Dent Assoc. 1997;128: 1128-1130.
3. Lockhart PB, Clark J. Pretherapy dental status of patients with malignant conditions of the head and neck. Oral Surg Oral Med Oral Pathol. 1994;77:236-241.
4. Oral complications of cancer therapies: diagnosis, prevention, and treatment. The National Institutes of Health Consensus Development Conference Statement. Oncology ( Williston Park). 1991;5:64, 69-76.
5. Meraw SJ, Reeve CM. Dental considerations and treatment of the oncology patient receiving radiation therapy. J Am Dent Assoc. 1998;129: 201-205.
6. Schubert MM, Epstein JB, Peterson DE. Management of oral complications during and after chemotherapy and/or radiation therapy. In: Yagiela JA, Neidle EA, Dowd FJ. Pharmacology and Therapeutics for Dentistry. 4th ed. St Louis: Mosby-Year Book Inc; 1998:644-655.
7. Guggenheimer J, Moore PA. Xerostomia: etiology, recognition and treatment. J Am Dent Assoc. 2003;134:61-69.
8. Samaranayake LP. Host factors and oral candidosis. In: Samaranayake LP, MacFarlane TW, eds. Oral Candidosis. London: Wright; 1990:66-103.
9. Wei SH, Yiu CK. Evaluation of the use of topical fluoride gel. Caries Res. 1993; 27(Suppl 1):29-34

From Dimensions of Dental Hygiene. January 2007;5(1): 28, 30.