Submandibular gland-sparing intensity-modulated radiotherapy.

Xerostomia is one of the most debilitating late effects of head and neck radiotherapy (RT) and significantly impacts quality of life. The submandibular gland (SMG) provides approximately 70% of the unstimulated saliva that accounts for about 95% of the salivary flow during a 24-hour period. Intensity-modulated RT (IMRT) has been used in recent years to lower the RT dose to the parotid gland(s) to reduce long-term xerostomia. There is little experience with SMG-sparing IMRT. Mean RT doses to the SMG exceeding 39 Gy cause permanent ablation of both stimulated and unstimulated salivary flow. Limited data suggest that SMG-sparing IMRT in selected patients results in reduced long-term xerostomia without increasing the risk of a local-regional recurrence.