PAROTID SPARING STUDY IN HEAD AND NECK-CANCER PATIENTS RECEIVING BILATERAL RADIATION-THERAPY - ONE-YEAR RESULTS

Many patients with head and neck cancers receive radiation therapy as part of their treatment which frequently causes considerable morbidity , including various degrees of permanent salivary gland dysfunction. T hree-dimensional treatment planning [3-DTP] and conformational dose de livery constitute a new therapeutic modality that conforms the high-do se radiation volume to the shape of the tumor volume while minimizing the dose to tissue that is not at risk of containing cancer. The treat ment volumes for head and neck tumors as well as parotid glands can be well-defined on cross-sectional CT imaging techniques. The purpose of this investigation is to determine if 3-DTP and conformational dose-d elivery could minimize radiation dose and salivary gland dysfunction t o contralateral parotid glands in patients with head and neck cancers. Eleven patients with head and neck cancers who required bilateral rad iation therapy were treated with 3-DTP. Unstimulated and stimulated bi lateral parotid saliva was collected prior to radiotherapy, weekly dur ing treatment, and 1, 3, 6, and 12 months after the completion of radi otherapy. Treated parotid glands received an average dose of 5745 cGy, while spared glands received only 1986 cGy (p < 0.0001). Unstimulated and stimulated parotid flow rates decreased dramatically in treated g lands after the initiation of radiotherapy, remained at extremely low rates without any improvements, and were significantly lower at 1 year after radiotherapy compared with baseline. Conversely, parotid flow r ates in spared glands underwent mild changes during radiotherapy and w ere approximately 50% of baseline values. The results of this study su ggest that with the use of 3-DTP, contralateral parotid gland function can be partially preserved for at least 1 year in patients with head and neck cancers requiring bilateral radiation.