Preemptive pharmacologic intervention in radiation-induced salivary dysfunction

Xerostomia ("dry mouth") is a symptom of several diseases. it also occurs a s a side effect of certain therapeutic interventions, most frequently pharm acotherapy, 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 therapeuti c 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 significa nt loss of stimulated flow makes it difficult to process solid food into a bolus that can be swallowed. If sustained, nutritional deficiencies may res ult. 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 under go radiation therapy for head and neck cancer in the United States each yea r. Increasing numbers are receiving total body radiation before transplanta tion of bone marrow. Although the salivary gland is not one of the more act ively dividing organs in the body, nevertheless it ranks as one of the mast radiosensitive. The mechanism of this sensitivity is not understood. This article reviews human and animal pathophysiology of radiation-induced saliv ary damage. We also discuss animal studies that have employed various strat egies to modify and clarify this process. Finally, we describe encouraging results from early clinical trials suggesting that protection of salivary g lands during therapeutic irradiation may be possible.