NCI monographs : a publication of the National Cancer Institute最新文献

Oral mucositis is a major toxic effect related to 5-fluorouracil (5-FU) therapy. Clinical studies have attempted to identify an effective antidote for this untoward side effect. Early pilot studies suggested that an allopurinol mouthwash could lessen 5-FU-induced mucositis. However, a randomized, double-blinded, placebo-controlled crossover study did not suggest that an allopurinol mouthwash had any prophylactic value in this clinical situation. An ongoing, randomized clinical protocol is testing cryotherapy as a method of inhibiting 5-FU-induced stomatitis. No clinically appropriate prophylactic measure for preventing 5-FU-induced mucositis has been found to date.

The initial effect of anticancer therapy, such as radiation and chemotherapy, is on the rapidly proliferating cells of the oral epithelium. As a consequence, the epithelium may show atrophy and ulceration. The sites of these alterations are related to the rate of epithelial proliferation. Regions of rapid proliferation, such as the oral lining mucosa, show a greater frequency of ulceration than masticatory mucosa or skin. Subsequent changes in the mucosa reflect damage to connective tissue, including fibroblasts and blood vessels. This results in hyalinization of collagen, hypovascularity, and ischemia. Indirect effects of anticancer therapy may include granulocytopenia and reduced salivary secretion, so that the protective mucin coating of the epithelium is compromised. These changes result in tissue with reduced barrier function and impaired ability to heal and to resist entry of pathogens, thus increasing the risk of systemic infections.

Oral complications of cancer therapy often have systemic consequences. Pain and discomfort are common and can lower intake of fluid and nutrients, which in severe cases can lead to dehydration and malnutrition, requiring hospitalization. Oral infections are frequent accompaniments of cancer treatment. Herpes simplex virus is the most common symptomatic oral viral infection, and, in latently infected patients the virus is frequently reactivated after cytoreductive therapy. Viral (infectious) oral mucositis is often indistinguishable from noninfectious mucositis. Bacterial infections are less commonly observed today, perhaps because of the routine use of empiric broad-spectrum antibiotics; however, many episodes of septicemia in neutropenic patients apparently originate from oral microorganisms. Fungal infections are frequent and are usually due to Candida species. Spread to the esophagus or systemic dissemination can occur. Noninfectious oral mucositis can be used as a marker of toxic effects in other organs, especially hepatic veno-occlusive disease. In bone marrow transplant patients with mucositis, hepatic veno-occlusive disease is six times more frequent than in such patients without mucositis.

New fever in a neutropenic patient mandates prompt institution of empirical broad-spectrum antibiotics. Traditional empirical regimens have relied on combinations that include an aminoglycoside. However, certain classes of newer antibiotics (e.g., third-generation cephalosporins, carbapenems, quinolones) include agents with a broad spectrum and high bactericidal activity that may provide therapeutic alternatives to combination regimens. We previously compared empirical monotherapy with ceftazidime to a combination regimen of cephalothin, gentamicin, and carbenicillin and found the regimens comparable with respect to percentage with success (survival without change of initial regimen; 62% vs 67%), success with modification (survival with additional antibiotics; 33% vs 29%) and failure (death; 5% vs 4%). Imipenem has a broader in vitro spectrum of activity than ceftazidime, particularly against gram-positive organisms and anaerobes, raising the possibility of equivalent or even improved efficacy as monotherapy. Accordingly, we are prospectively randomizing febrile, neutropenic patients to either empirical ceftazidime or imipenem therapy. Imipenem appears to be comparable to ceftazidime in this ongoing study but has not resulted in fewer modifications or secondary infections. Studies assessing the role of quinolones in the management of neutropenic patients are under way.

Osteoradionecrosis (ORN) is one of the most serious complications arising from head and neck radiation therapy. Current research has shown that ORN represents nonhealing, dead bone and is not a state of infection. ORN is the result of functional and structural bony changes that may not be expressed for months or years. ORN may occur spontaneously or in response to wounding. Predisposing factors include absorbed radiation dose, fractionation, delivery modality, and dental status. Timing of dental extractions and other factors have also been shown to affect incidence. ORN may be reduced through early intraoral evaluation, treatment, and adequate healing time prior to beginning RT. Hyperbaric oxygen (HBO) therapy has been beneficial in the prevention and treatment of ORN. It is of paramount importance for the medical community to recognize the factors that may reduce ORN incidence, endorse oral care protocols, and acknowledge the value of HBO therapy in the prevention and treatment of this disease.

This article reviews the prevention of oral and systemic infection in bone marrow transplantation and radiation patients. Prophylaxis of herpes virus reactivation in bone marrow transplant and leukemic patients has resulted in reduced morbidity associated with their medical management. In order to reduce the risk of systemic infection, reduction in ulcerative mucositis is desirable. The use of antifungal and antibacterial agents has not been encouraging to date. Cytoprotective agents have shown some initial success in preventing mucosal breakdown. Further study is required to confirm these initial results.

Acute and chronic graft-versus-host disease (GVHD) are significant complications of allogeneic bone marrow transplantation that occur when immunologically active T-cell lymphocytes are transplanted into an immunosuppressed recipient who is genetically disparate from the marrow donor. Oral GVHD lesions closely resemble those seen with a number of autoimmune connective tissue disease, including lichen planus, systemic sclerosis, lupus erythematosus, and Sjögren's syndrome. Mucosal erythema, atrophy, and ulceration are noted clinically; lichen planus-like lesions are the most distinctive oral lesions. Salivary gland changes include changes in both flow rate and sialochemistry. Oral involvement ranges between 33% and 75% for patients with acute GVHD and upwards of 80% for those with chronic GVHD. Management of oral GVHD lesions depends on successful systemic therapy, although topical steroids can be of help in some instances.

Chlorhexidine's structural characteristics give it potent antimicrobial activity, effectiveness at low concentrations, substantivity that prolongs its therapeutic effect in the oral environment, minimal resorption from the gastrointestinal tract, and the ability to reduce plaque. The use of this agent for oral stomatitis in neoplasia patients has recently been studied. Treatment-associated oral soft tissue inflammation and ulceration were significantly reduced by chlorhexidine in patients undergoing intensive chemotherapy. Reductions in total streptococci and yeast counts were also observed. When used in conjunction with systemic antifungal agents, such as nystatin or clotrimazole, a significantly decreased incidence of clinical oral candidiasis and Candida septicemia was observed. In contrast, in two studies in which high-dose head and neck radiation therapy was applied, there was no reduction in stomatitis. Oral gram-negative bacilli have been shown to increase in high-dose chemotherapy patients who are taking chlorhexidine during the treatment period (3 wk to 2 mo). However, no increase in systemic gram-negative infections or other adverse negative medical consequences were observed. This agent appears to be of therapeutic benefit in reduction of dental plaque, gingivitis, and stomatitis in the high-risk chemotherapy population when used in conjunction with other topical and systemic antimicrobial agents as prophylaxis. Although no toxic or serious adverse effects of chlorhexidine rinse have been observed in the short-term studies to date, the effects of longer-term chlorhexidine administration should be evaluated.

Taste and olfaction provide sensory information and sensory pleasure. Cancer therapies affect both. Chemotherapy has not been shown to produce dramatic losses of taste or smell, but systematic studies on various chemotherapeutic agents and types of cancer are lacking. Radiation therapy does produce clear losses of both taste and smell. Both chemotherapy and radiation therapy alter the pleasure produced by taste and smell through the formation of conditioned aversions. That is, foods consumed in proximity with the nausea of therapy come to be unpleasant. The impact of conditioned aversions can be diminished by providing a scapegoat food just before therapy. Alterations in foods may be beneficial to the cancer patient. Increasing the concentrations of flavor ingredients can compensate for sensory losses, and providing pureed foods that retain the cognitive integrity of a meal can benefit the patient who has chewing or swallowing problems.