Preemptive pharmacologic intervention in radiation-induced salivary dysfunction.

Abstract

Xerostomia ("dry mouth") is a symptom of several diseases. It also occurs as a side effect of certain therapeutic interventions, most frequently pharmacotherapy. The most severe and irreversible forms of salivary dysfunction result from damage to or loss of salivary acinar cells. One of the severest forms of iatrogenic salivary gland destruction results from the therapeutic doses of irradiation given to treat head and neck cancer or to purge the bone marrow before transplantation. Xerostomia encompasses a wide range of involvement, from an inconvenience when mild, to a debilitating condition when severe. Reports of the symptom of dry mouth by patients do not always correlate with the degree of diminished salivary flow. However, a significant loss of stimulated flow makes it difficult to process solid food into a bolus that can be swallowed. If sustained, nutritional deficiencies may result. Saliva also facilitates formation of speech patterns. Its loss hinders speaking and communicating, possibly causing the patient to withdraw from social interaction. Together these conditions can impair the physiological and psychological well-being of the patient. Thousands of individuals undergo radiation therapy for head and neck cancer in the United States each year. Increasing numbers are receiving total body radiation before transplantation of bone marrow. Although the salivary gland is not one of the more actively dividing organs in the body, nevertheless it ranks as one of the most radiosensitive. The mechanism of this sensitivity is not understood. This article reviews human and animal pathophysiology of radiation-induced salivary damage. We also discuss animal studies that have employed various strategies to modify and clarify this process. Finally, we describe encouraging results from early clinical trials suggesting that protection of salivary glands during therapeutic irradiation may be possible.