The oral cavity has the potential to be a major source of short-term and long-term complications from cancer therapy. Appropriate evaluation and elimination of potential sources of oral infection before cancer therapy is vital because oral bacteria are a known source of bacteremia and septicemia during cancer therapy. Cancer diagnosis with previous and planned treatment, past medical history, past dental history, current medications, drug allergies, social history, family history, laboratory values, extraoral findings, intraoral findings, and radiographic findings must all be evaluated in planning dental treatment for these complex cases.
The management of dental disease before and during cancer therapy poses many challenges to the dental practitioner. Cancer therapy has numerous potential short-term and long-term oral complications that may require modification of dental management strategy. Dental treatment may also require modification in situations where it must be delivered expeditiously and there is little time to institute an ideal treatment plan. For example, patients first diagnosed with acute leukemia begin induction chemotherapy within days of their diagnosis and will not have sufficient time for elective therapy and elimination of all sources of dental disease. During chemotherapy when white blood cell (WBC) counts are low, a dentist may elect to treat a dental infection with antibiotics rather than an extraction. In spite of this, pretherapy dental evaluation consisting of a good history, examination, and oral radiographs provide a baseline assessment that may be helpful if problems occur during cancer therapy.
Dental management of a patient in preparation for cancer therapy
The need for conducting a pretreatment oral evaluation depends on the cancer diagnosis and planned cancer therapy. Patients diagnosed with solid tumors (such as breast, prostate, lung, or colon cancers—the most common cancers in the United States) are not typically evaluated. Patients who are most frequently seen before chemotherapy or radiation are those who are at the highest risk for developing short-term and long-term complications as outlined above. These include the following:
- (1)
Patients undergoing chemotherapy followed by hematopoietic stem cell transplantation (HSCT) . Conditioning regimens for HSCT are generally myeloablative and place the patient at high risk for infectious complications during the period of pancytopenia. Autologous HSCT is used to treat lymphoma, multiple myeloma and some metastatic solid tumors to the marrow. In this procedure, the patient’s own stem cells are collected before conditioning, and then reinfused to reconstitute the marrow that has been ablated by chemotherapy. Allogeneic HSCT is generally performed in patients with leukemia or bone marrow failure syndromes such as aplastic anemia where the diseased marrow is replaced by healthy marrow from a donor. Following allogeneic HSCT, patients may be immunosuppressed in the long term because of prophylaxis for chronic graft-versus-host disease (GVHD), slow immune reconstitution, and treatment for chronic GVHD.
- (2)
Patients who require head and neck radiation therapy. Head and neck cancers that are typically treated with head and neck radiation therapy include squamous cell carcinoma, salivary gland malignancies, and lymphoma. Radiation at therapeutic doses induces long-term irreversible damage to the salivary glands, connective tissues, vasculature, and healing potential of the jawbones, and in particular the mandible.
The following are the goals of dental management before the start of cancer therapy.
Eliminate or stabilize oral disease to minimize local and systemic infection during and after cancer therapy
Short term
Cytoreductive therapy generally leads to low WBC counts and in particular low neutrophil counts (neutropenia), which increases susceptibility to infection, in particular bacterial infections. Since most odontogenic infections such as caries, periodontal infection and third molar infections are usually of bacterial origin, elimination of potential sources of infection from the oral cavity is a key strategy to prevent new infections or exacerbation of existing chronic infections . Ideally, all patients should be returned to a stable, if not perfect state of dental health before cytoreductive therapy.
Mucosal injury or mucositis is a common side effect of cancer therapy and removal of sharp edges of teeth or restorations may help to reduce trauma to the mucosa and reduce the severity of mucositis and attendant pain and discomfort. Furthermore, ulcers of mucositis may act as a gateway for ingress of oral bacteria in profoundly myelosuppressed individuals with the potential for bacteremia and septicemia . The frequency of viridans streptococci in neutropenic patients has become more common, with Streptococcus mitis being the most common species identified . Up to one third of viridans streptococci–infected patients can develop shock syndrome .
Long term
Radiation therapy to the head and neck has the potential for increased caries risk and reduced healing capacity (especially of the bone) in the long term . Elimination of dental disease by judicious restorative dentistry and periodontal treatments, and extraction of teeth with questionable prognosis are important preventive strategies to avoid future dental extractions, an important risk factor for postradiation osteonecrosis. Custom trays for prescription fluoride applications are often fabricated for patients since lifelong fluoride therapy helps to minimize radiation-induced dental caries. Patients treated with intravenous (IV) bisphosphonates are at risk for developing bisphosphonate-related osteonecrosis of the jaws . Because invasive dental procedures such as extractions are a risk factor for this condition, elimination of dental disease to reduce the necessity for such dental procedures in the long term is an important aspect of patient management.
Patients who undergo allogeneic hematopoietic stem-cell transplantation may develop chronic GVHD (see the article by Schubert and Correa elsewhere in this issue). This disease may result in painful mucosal ulcerations, increased caries rates, hyposalivation, and sometimes fibrosis, limiting mouth opening. Similar to patients with radiation-induced salivary gland hypofunction, caries even when incipient must be treated and dental treatment should not be deferred.
Identify issues specific to the cancer diagnosis
A thorough examination of the mouth for oral involvement of the primary tumor such as leukemic infiltrates (especially in the gingiva) and jaw involvement from multiple myeloma should be performed. Such oral involvement that may not have been noted previously may change the stage of the patient’s disease and impact future cancer therapy.
Educate the patient regarding short-term and long-term oral complications from cancer therapy
This provides an opportunity to educate the patient about the role of dental health in systemic disease. Patients should be informed about why a dental evaluation is important before cancer therapy, what to expect during cancer therapy (such as mucositis and xerostomia), and measures that can be taken to minimize side effects of therapy. The importance of long-term follow-up should also be stressed, especially with respect to postradiation caries and osteonecrosis, bisphosphonate-related osteonecrosis of the jaws, and chronic GVHD in the appropriate patient population. Written information is usually helpful for patients and many cancer centers provide such information for patient education. The National Institutes of Health provides information and pamphlets free of charge at the following Web site: .
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