Management
Oral Management of the Patient With Cancer in the Head and Neck Region
Bruce F. Barker, DDS, and Gerry J. Barker, RDH, MA
Copyright 2001 Journal of the California Dental Association.
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Cancer therapies -- including surgery, radiation, and chemotherapy -- may unfavorably affect the oral/dental health of patients. Existing dental problems can also result in serious complications that may be prevented by dental intervention prior to cancer therapy. This paper will be limited to a discussion of the detrimental effects of radiation therapy on the oral cavity and salivary glands and appropriate dental management.
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A patient calls a dental office for an appointment before beginning cancer therapy for a cancer in the head and neck region. The dentist may or may not receive a consultation from an oncologist. What are the questions the dentist needs to ask? What are the dental implications? What should the dentist recommend? Dentists who have not been confronted with these questions may be in the near future. The oral cavity can be affected by therapy for any cancer in the head and neck region, including cancers of the oral cavity, pharynx, larynx, thyroid, esophagus, and lymph nodes, including lymphomas and Hodgkin’s disease. Radiation treatment for some types of brain cancer may affect the tissues of the mouth or salivary glands. While not related to the topic of this paper, it should be noted that chemotherapy or bone marrow/stem cell transplantation for other malignancies also requires dental consultation to prevent or ameliorate serious complications, especially systemic infection.1,2
Most head and neck cancers are treated with surgery and/or radiation therapy and sometimes adjuvant chemotherapy. The effects of surgical treatment are immediately obvious, but radiation therapy may result in both acute and long-term consequences to the oral mucosa, salivary glands, teeth, and bone. This discussion will be limited to the oral effects of radiation in the treatment of all head and neck malignancies.
It is critical that the dentist not delay a patient’s requested dental appointment. Radiation therapy should not be initiated until the dentist has completed a dental evaluation. Prior to seeing the patient, the dentist will want to contact the radiation oncologist and ask the following questions:
* What is the type of cancer, and where is it located?
* What is the proposed total dose of radiation, and what are the exact anatomic areas to be radiated?
* How much radiation will the jaws, teeth, and salivary glands receive?
A referral form requesting this information on a diagram of the head has been published.3 Most cancers receive from 4,000 to 7,200 cGy (centigrays: 1 cGy = 1 rad.) This radiation is typically delivered five days a week in doses ranging from 180 to 200 cGy per day. The dentist’s concern is for any patient who receives more than 4,000 cGy to salivary glands and more than 5,500 cGy to maxillary and mandibular bone. These doses may result in serious side effects, some of which may be permanent.4,5
Oral and Dental Effects of Radiation Therapy to the Head and Neck
Within the first two weeks, the direct effect of radiation therapy on oral soft tissue results in mucositis, edema, erythema, ulceration, and pain (Figure 1). Tissue breakdown causes difficulty in eating and secondary infections. Mucositis persists throughout radiation therapy but resolves within weeks after completion of therapy.
Salivary glands that receive more than 4,000 cGy may be permanently destroyed.6 It is very important to find out which glands will be within the field of radiation. If the parotids, submandibular, sublingual, and minor glands are radiated, there will likely be severe salivary gland hypofunction. Even radiation to only a portion of the salivary gland tissue, such as that administered for thyroid and laryngeal cancer and lymphoma of the neck, may result in permanent salivary gland damage and severe adverse oral effects. Salivary flow does not improve after completion of therapy, and dysfunction may actually worsen with time.1,7,8,
The results of a change in the quantity and quality of saliva are numerous, including alteration of taste (dysgeusia), increased mucosal infections, difficulty in swallowing, decreased oral pH, enamel demineralization, and rampant radiation caries. While taste loss and infections diminish after therapy, the risk of demineralization/rampant caries persists throughout life. Typically, the teeth begin to break down at the cervical margins and incisal edges and progress rapidly (Figures 2 and 3). An oral hygiene program that will be discussed later can prevent breakdown of the teeth. Recently, some pharmacological interventions have been introduced during radiation therapy in attempt to preserve the salivary gland function, including sialogogues such as Salagen and a radioprotective agent, amifostine. These drugs are effective and should be offered to the patient.
The direct effects of radiation on the muscles of mastication and the TMJ may result in fibrosis and trismus leading to limited mouth opening and future oral care problems. Simple exercises may reduce the severity of trismus.
For patients receiving more than 5,500 cGy to the jaws, the most serious and devastating complication is osteoradionecrosis. The risk increases as the dose of radiation increases. It was previously believed that osteoradionecrosis was an infection or osteomyelitis. Studies have established that it is due to the bone’s inability to heal properly because of the effects of radiation on blood vessels, fibroblasts, and osteoblasts. This has been called the "triple H effect" or hypovascularity, hypoxia, and hypocellularity.9 As a result, the bone and connective tissue lose their capacity to heal or repair tissue damage. There is an increased risk of osteoradionecrosis in the mandible because it is less vascular than the maxilla and because its density results in a higher absorbed dose of radiation.5 Some cases are spontaneous, but most are the result of trauma such as tooth extraction and denture irritation after radiation therapy.
What are the implications of osteoradionecrosis to the dentist? A patient that reports radiation therapy of more than 5,500 cGy to tooth-bearing areas is at risk. Osteoradionecrosis caused by tooth extraction usually occurs within three months to five years after completion of radiation therapy.4 The risk of osteoradionecrosis does not disappear with time and may occur years after radiation therapy.10
Preradiation-Therapy Dental Evaluation and Treatment
What can be done to reduce or eliminate some of the problems discussed? The most important is that every patient undergo a preradiation-therapy dental evaluation. A 1989 National Institutes of Health Consensus Conference recommended that all cancer patients have an oral exam before initiation of therapy.1
Table 1 lists the suggested strategies for a preradiation-therapy dental evaluation. Intra- and extraoral soft tissue exams, periodontal probing, caries evaluation, and radiographs with panoramic and selective periapical films should be done. Because the risk for osteoradionecrosis does not diminish with time, the dentist needs to predict what teeth might need to be extracted at any time during the patient’s life. To avoid possible complications of osteoradionecrosis, all questionable teeth in the proposed radiation field should be extracted prior to radiation therapy. Teeth that exhibit advanced caries, periapical pathology, or advanced periodontal disease, including molar teeth with furcation involvement, should be extracted. Full bony impacted teeth do not need extraction; however, partially impacted teeth should be removed. Increased caution should be employed for patients who exhibit poor oral hygiene, poor compliance with prior dental recommendations, or greater than 50 percent periodontal bone loss. Prosthetic considerations such as undercuts and tori need to be addressed prior to radiation therapy. It is necessary to delay radiation therapy for 14 to 21 days after oral surgery to allow for healing.10 Inadequate healing time can result in a higher incidence of osteoradionecrosis. The radiation oncologist should be consulted prior to any invasive dental procedures.
Salivary flow and the normal constituents of saliva will be permanently changed following radiation. As a result, there is likely to be an increased incidence of dental caries, demineralization of enamel, and candidiasis. Patients should be cautioned that dental caries and demineralization might dramatically increase with the consumption of a highly cariogenic diet or beverages containing sugar, phosphoric acid, or citric acid. This includes most dietary soft drinks.
Custom fluoride carriers should be fabricated for all dentulous patients receiving more than 4,000 cGy to salivary glands. These vacuum-formed carriers are made from flexible vinyl mouthguard material and should cover the cervical margins of the teeth and have smooth edges that will not irritate adjacent gingival tissue. The authors recommend a 1.1 percent sodium fluoride gel that is spread in the carriers and applied to the teeth for five minutes a day. Following application of the gel, the carriers are removed and washed; but the patient should not rinse or eat for 30 minutes.3
If time permits, the patient should have dental prophylaxis before therapy begins. Oral hygiene instructions should be tailored to meet the needs of the patient, especially those patients who have had surgery and limited opening.
All patients should be evaluated for tobacco and alcohol use that may contribute to a recurrence of or new primary oral and pharyngeal cancer as well as worsen oral complications of radiation to the oral mucosa.11 Cessation counseling should be offered.
Oral Care During Radiation Therapy
Oral complications become more severe as the patient progresses through the weeks of therapy. Early management of mucositis and infection may alleviate pain and prevent the necessity of interruption of radiation therapy to allow for healing of mucosal lesions. Routine and consistent oral cleansing to reduce microbial burden, replacement of moisture, and use of topical anesthetics and analgesics are typically recommended.
Emphasis should be placed on the importance of keeping the mouth as clean and moist as possible throughout therapy.12-15 Regular tooth brushing and flossing should continue until the mouth is too ulcerated to tolerate the trauma of a toothbrush and the strong flavoring agents of toothpaste. An alternative is gentle cleansing of the teeth and oral tissues with gauze moistened with a baking soda water solution (1 teaspoon of baking soda to 1 pint of water.) This solution is mucolytic and may be used as a gentle rinse several times a day.
Many oncologists prefer the use of topical anesthetics such as viscous xylocaine, but the authors prefer other agents that will not impair swallowing and lead to aspiration pneumonia. The authors’ standard has been a 50/50 mixture of alcohol-free Benadryl and a coating agent such as Maalox or Mylanta. Patients can use this as needed, and they repeatedly acknowledge its effectiveness.
Evidence of mucositis outside of the radiation field or a significant increase in pain may indicate candidiasis, viral, or bacterial infection. Cultures are the gold standard for diagnosis. Antifungal rinses that are high in sucrose should be avoided due to the high cariogenic potential. Patient compliance with taking fluconazole 100 mg (2 tablets on day one, then one tablet for six to 13 days) is greater than with sucrose-rich nystatin suspension or clotrimazole troches, which are difficult to dissolve in the mouth.
Trismus is a late result of the direct effect of radiation to the muscles of mastication and possibly the temporomandibular joint. Limited mandibular opening may result, with reductions of 10 to 15 mm of opening. A simple regimen of exercising the muscles three times daily by opening and closing the mouth 20 times without pain may prevent or reduce the severity of trismus. If difficulties in opening do develop, dynamic bite openers are beneficial.4
Dental Management Following Radiation Therapy
At the end of therapy, complications will begin to improve but may linger for a month or two. Xerostomia, however, persists and generally will show little improvement with time because the salivary gland acini may be permanently destroyed. Therefore, maintenance of excellent oral hygiene and daily fluoride gel treatments using custom-fit carriers must continue throughout life. Dental recall should be frequent for early intervention in dental complications. Scaling and root planing can continue to prevent progression of periodontal disease. If caries develop despite daily fluoride treatments, the addition of a calcium-phosphate remineralizing gel such as Revive should be recommended. Additionally, a fluoride varnish should be applied to the entire dentition and a two-week course of chlorhexidine rinse recommended to suppress cariogenic bacteria.16 Patients must adhere to a noncariogenic diet for maintenance of a healthy dentition. Sialogogues, commercial saliva substitutes, and frequent sips of water may help alleviate the discomfort of xerostomia.
The greatest concern is osteoradionecrosis. While spontaneous osteoradionecrosis may occur with high doses of radiation, the most common cause is from the trauma of tooth extraction. Other invasive procedures or ulceration from a dental appliance may also precipitate osteoradionecrosis. Teeth can never be safely extracted from bone that has received more than 5,500 cGy without the risk of osteoradionecrosis. If oral surgery is necessary, the standard of care in the United States is referral to a physician for hyperbaric oxygen therapy prior to the surgery.5,10 Malpractice settlements have been awarded for failure to use hyperbaric oxygen therapy.17 Twenty such treatments of 100 percent oxygen under pressure are recommended prior to tooth extraction with 10 to 20 additional treatments following surgery. Treatments are costly and do not ensure prevention of osteoradionecrosis. If it does develop, additional hyperbaric oxygen may be necessary and/or resection of the involved bone.18 There appears to be a significant reduction in risk of osteoradionecrosis for single tooth extractions. An alternative to extraction for a single tooth is amputation of the crown and root canal therapy.4
Conclusion
Responding to the needs of dental patients receiving cancer therapy is critical. This manuscript discusses the effects of radiation therapy to the oral tissues and their management. The dentist’s care must be immediate and appropriate to ameliorate acute oral complications and prevent serious long-term sequelae. Patients receiving chemotherapy or bone/stem cell transplantation may also have serious oral complications that are beyond the scope of this paper.
Author
Bruce F. Barker, DDS, is a professor in the Department of Oral and Maxillofacial Pathology at the University of Missouri-Kansas City School of Dentistry.
Gerry J. Barker, RDH, MA, is an associate professor in the Department of Dental Public Health and Behavioral Science at UMKC School of Dentistry.
References
1. National Institutes of Health Consensus Development Panel Consensus statement: oral complications of cancer therapies: diagnosis, prevention and treatment. National Cancer Institute Monograph No 9, 1990.
2. Barker GJ, Current practices in the oral management of the patient undergoing chemotherapy or bone marrow transplantation. Support Care Cancer 7:17-20, 1999.
3. Barker GJ, Barker BF, Gier RE, Oral Management of the Cancer Patient, A Professional Guide for the Management of Patients Undergoing Chemotherapy and Head and Neck Radiation Therapy, 6th ed. University of Missouri-Kansas City, Kansas City, Mo, 2000. Available only through Colgate Oral Pharmaceuticals.
4. Beumer J, Curtis TA, Marunick MT, Maxillofacial Rehabilitation, Prosthodontic and Surgical Considerations. Ishiyaku EuroAmerica, St. Louis and Tokyo, 1996.
5. Scully C, Epstein JB, Oral health care for the cancer patient. Oral Oncol Eur J Cancer 32B(5):281-92, 1996.
6. Liu RP, Fleming TJ, et al, Salivary flow rates in patients with head and neck cancer 0.5 to 25 years after radiotherapy. Oral Surg Oral Med Oral Pathol 70:724-9, 1990.
7. Dreizen S, McCredie KB, et al, Oral complications of cancer radiotherapy. Postgrad Med 61:85-92, 1977.
8. Valdez IH, Atkinson JC, et al, Major salivary gland function in patients with radiation-induced xerostomia: Flow rates and sialochemistry. Int J Radiation Oncology Biol Phys 25:41-7, 1992.
9. Marx RE, Osteoradionecrosis: A new concept of its pathophysiology. J Oral Maxillofac Surg 41:283-8, 1983.
10. Marx RE, Johnson RP, Studies in the radiobiology of osteoradionecrosis and their clinical significance. Oral Surg Oral Med Oral Pathol 64:379-90, 1987.
11. Rugg T, Saunders MI, et al, Smoking and mucosal reactions to radiotherapy. Brit Jour Radiology 63:554-6, 1990.
12. Martin MV, Irradiation mucositis: A reappraisal. Oral Oncol Eur J Cancer 29B(1):102, 1993.
13. McIlroy P, Radiation mucositis: A new approach to prevention and treatment. Eur J Cancer Care 5(3):153-8, 1996.
14. Epstein JB, Van der Meij, Complicating mucosal reactions in patients receiving radiation therapy for head and neck cancer. Spec Care Dent 17(3):88-93, 1997.
15. Jansma J, Vissink A, et al, Protocol for the prevention and treatment of oral sequelae resulting from head and neck radiation therapy. Cancer 70(8):2171-80, 1992.
16. Rankin KV, Jones DL, eds, Oral Health in Cancer Therapy. A Guide for Health Care Professionals. Dental Oncology Education Program. Texas Cancer Council, Dallas TX, 1999.
17. Spaeth D, Jury awards nearly $3 million in Florida malpractice lawsuit. ADA News 25(9):14, May 2, 1994.
18. Cronje FJ, A review of the Marx protocols: Prevention and management of osteoradionecrosis by combining surgery and hyperbaric oxygen therapy. South African Dent J 53(10):469-71, 1998.
To request a printed copy of this article, please contact/Bruce F. Barker, DDS, University of Missouri-Kansas City School of Dentistry, 650 E. 25th St., Kansas City, MO 64108 or at barkerb@umkc.edu.
Figure 1. Severe oral mucositis with ulceration that developed in the third week of radiation therapy.
Figure 2. Radiation-type caries at the cervical margins. Several teeth exhibit circumferential caries that will lead to amputation of the tooth at the gingival.
Figure 3. Severe demineralization and caries that developed within months of undergoing mantle field radiation therapy for Hodgkin’s disease. The radiation therapy involved a portion of the salivary glands but not the teeth.
Table 1. Strategies for Preradiation-Therapy Dental Evaluation
* Radiographs, including panoramic and selective periapicals
* Extra- and intraoral soft-tissue exam for surgical defects, compromised vascularity, infection, recurrent or additional cancer.
* Periodontal evaluation for furcation involvement, mobility, or greater than 50 percent bone loss
* Existing carious lesions and faulty restorations
* Oral hygiene and previous dental compliance
* Cariogenic/xerogenic diet and medication analysis
* Tobacco and alcohol use
* Psychosocial issues that may affect future compliance
