Commentary (Zlotolow): Minimizing Oral Complications of Cancer Treatment

Minimizing oral manifestations of cancer treatment is a major concern for both dentists and physicians. This article, by dentists from the M. D. Anderson Cancer Center in Houston, Texas, addresses the prevention and minimization of oral complications by describing their observations and considerations for a wide range of oncologic treatments.

The oncologic dentistry staff at M. D. Anderson has promoted awareness of oral complications for 20 years. One aspect that has not been addressed previously is physician recognition. To improve physician awareness of the oral cavity, it is essential to discuss prevention by specific disease entity, specific systemic cancer therapy, and specific pretreatment dental/oral condition.

Pediatric oncologists should be advised of the importance of growth and development [1], eruption patterns, caries rates, parental habits, and diet. Dental oncologists must be aware of the importance of the timing of chemotherapy and expectations of hematologic nadirs and their rebound, so that they can appropriately schedule the initial dental examination and any subsequent treatments. Ideally, patients should be examined 14 to 21 days prior to beginning anticancer therapy.

A dialogue between the oncologist and dental team is imperative: The physician should inform the dental team about the expected medical treatment outcome; the dental team should explain to the physician any oral or dental conditions that may impact on that outcome, for example, the difference in healing potentials between a periodontally involved tooth with class III mobility requiring extraction and a bony impacted third molar. The role of the dental oncologist as described in this paper is excellent, and a similar philosophy is followed at Memorial Sloan-Kettering Cancer Center.

In the section on chemotherapy, the authors discuss stomatitis and the need for culture identification of the ensuing problem. Oral tissue and blood cultures usually are not correlated, and the physician typically prescribes empiric treatment for the stomatitis. At times of hematologic nadir and/or fever, dental treatment could be more of a risk for bacteremia and/or septicemia, especially during immunosuppression and/or thrombocytopenia.

Mucositis Usually Unavoidable

Mucositis that arises during the treatment of hematologic disease with intensive chemotherapy, total-body irradiation, or allogeneic bone marrow transplant is usually predictable and unavoidable. Although cultures for specific microorganisms are intelligently advised, oncologists usually do not wait for laboratory results before prescribing treatment. Most oncologists prophylactically treat patients who develop mucositis with antibiotics, antifungals, and antivirals due to expediency of control of the cancers. That is, the cause of the mucositis, the chemotherapy, needs to be continued.

A careful review of studies of chemotherapy-induced mucositis reveals the following:

• Most study populations are not homogeneous.
• Most study designs are not double-blinded or placebo-controlled.
• Many subset analyses have not been investigated with regard to staging, histopathology, age, sex, and treatment modalities.

Moreover, we currently lack standard scales for measuring mucositis. Also, thus far, studies utilizing nonsteroidal agents and coating agents, such as sucralfate (Carafate), have had conflicting results. Finally, claims that chlorhexidine (Peridex) reduces mucositis in both irradiated patients and leukemia patients receiving bone marrow transplants have not been not verified.

The authors emphasize that ultrasoft toothbrushes can be safely used by patients with chemotherapy-induced thrombocytopenia, and that there is no evidence of hemorrhage associated with their use. We concur with this assessment based on our observations of similar patients at Memorial Sloan-Kettering.

Empiric Use of Hyperbaric Oxygen Not Recommended

In patients receiving radiation therapy to the head and neck, there is an enormous range of portal fields, fractionations, total dosage, and specific disease criteria. Many oral surgical pro- cedures, such as extractions and soft-tissue surgery, are relatively safe in these individuals. To reduce the risk of osteoradionecrosis, hyperbaric oxygen should be recommended only when required by the degree of bone and soft-tissue involvement. It should not be used empirically.

No controlled, prospective clinical trials have assessed the efficacy of hyperbaric oxygen, and all reports attesting to its effectiveness are anecdotal. Further, well-designed studies need to verify the positive results described by Marx [2,3]. Individual cases of osteonecrosis are usually complicated by so many etiologic and treatment variables that it becomes difficult to separate out the effects of hyperbaric oxygen alone. We concur with Schwartz [4] that, before hyperbaric oxygen becomes a "standard of care," it must undergo unbiased investigations, the methodology and results of which must survive vigorous scientific analysis and scrutiny.

In the meantime, careful wound care, debridement, and appropriate reconstruction of bony and soft tissue defects can lead to successful results in patients with osteonecrosis.

Dental Team's Role in Radiotherapy and Surgery

The M. D. Anderson group has led the way in setting the standard of fluoride use in the prevention of radiation-induced caries in the xerostomic head and neck cancer patient. The Dreizen study of 1977 is considered a major therapeutic breakthrough [5]. However, most patients' long-term compliance with gel tray regimens for applying fluoride is actually very poor. Compliance with fluoride is an issue with which the dental team and patient must come to terms.

At Memorial Sloan-Kettering, we established "Standards of Care Practice Guidelines" that require attending staff to refer all patients scheduled for head and neck irradiation or bone marrow transplants to the Dental Service before treatment. All patients are evaluated weekly during their radiation therapy to maintain compliance with fluoride application and hygiene. Monitoring continues on a monthly basis for the first 6 months post-treatment, with dental appointments coinciding with radiation therapy, bone marrow transplantation, and/or pediatric oncology follow-up visits. This sequence establishes a pattern for continuity of care, possibly leading to less severe late oral manifestations of cancer therapy.

The practice guidelines also state that the dental diagnostic evaluation, prevention via prophylaxis and scaling, oral hygiene instructions, restorative procedures, and extractions are integral components of the patient's cancer therapy. Many medical decisions about the type and timing of cancer therapy are based on the dental/oral findings and recommendations made at the time of referral or at periodic oral examinations.

All patients who are expected to undergo maxillofacial prosthetic intervention are seen preoperatively by an attending dentist, as requested by the head and neck surgeons. This preoperative consultation includes a standard examination, radiographs, and impressions of teeth and hard and soft palate. Our attending dentists also are asked by the head and neck and reconstructive surgeons to be present in the operating room at specific times, to undertake prosthetic and/or dental intervention.

Patients who undergo maxillofacial prosthetic intervention are followed postoperatively for maintenance and follow-up in conjunction with their postsurgical appointments, sometimes as often as two to three times a week during the immediate postoperative phase. This follow-up system has enabled us to prevent, eliminate, or decrease acute or late manifestations of cancer therapy (eg, nasal regurgitation or mucosal ulcerations at surgical margins).

Summary

In summary, availability, accessibility, and visibility of the dental team members and their relationships with medical, surgical, and radiation oncologists are the keys to preventing oral complications. Preventive dentistry and an ongoing dialogue between physicians and dentists are essential for improving quality-of-life issues. Minimizing oral complications of cancer treatment is a reality. Standards of care need to be established to promote prevention. The M. D. Anderson Dental Oncology Group should be commended for bringing into focus this often neglected area of preventive therapy.

References:

1. Sonis AL, Tarbell N, Valachovic RW, et al: Dentofacial development in long term survivors of acute lymphoblastic leukemia: A comparison of three treatment modalities. Cancer 66:2645-2652, 1990.

2. Marx RE: Osteoradionecrosis: A new concept of its pathophysiology. J Oral Maxillofac Surg 41:283-288, 1983.

3. Marx RE: A new concept in treatment of osteoradionecrosis. J Oral Maxillofac Surg 41:351-357, 1983.

4. Schwartz HC: Treatment of osteoradionecrosis with measures other than hyperbaric oxygen. Proc First Int Cong Maxillofac Prosthet 192-198, 1995.

5. Dreizen S, Brown LR, Daly TE, et al: Prevention of xerostomia-related dental caries in irradiated cancer patients. J Dent Res 56:99, 1977.