Sparing of the submandibular glands by intensity modulated radiotherapy in the treatment of head and neck cancer

Background and purposeThe submandibular glands produce most of the unstimulated saliva output and are the key in prevention of radiation-related xerostomia. We investigated whether sparing of the submandibular function is feasible with intensity modulated radiotherapy (IMRT).Patients and methodsThirty-six patients diagnosed with head and neck cancer were treated with IMRT and had at least one parotid gland excluded from the planning target volume. In a subset, of these patients (n=18) where the risk of cancer recurrence in the contralateral submandibular region was judged low, the contralateral submandibular gland was spared from full-dose irradiation. The total unstimulated and stimulated salivary flow rates and adverse effects were monitored.ResultsTwelve months following IMRT mean unstimulated saliva flow was 60% of the baseline value among patients who had one submandibular gland spared and 25% among those who did not (P=0.006). Patients whose contralateral submandibular was spared reported less grade two or three xerostomia (4 vs. 11; P=0.018), and used less saliva substitutes. No cancer recurrences were detected at the vicinity of the spared glands during a median follow-up time of 31 months.ConclusionsSubmandibular gland sparing with IMRT is safe in selected patients treated for head and neck cancer. It is effective in prevention of radiation-associated xerostomia.