Failure in region of parotid gland after definitive intensity-modulated radiotherapy for Nasopharyngeal Carcinoma / 中华放射肿瘤学杂志

ABSTRACT

To investigate the potential risk factors for parotid gland failure after intensity-modulated radiotherapy (IMRT) for nasopharyngeal carcinoma (NPC).Methods The clinical data of 1096 NPC patients who underwent IMRT in our hospital from January 2005 to December 2012 were analyzed retrospectively.Among these patients, 13 patients experienced parotid gland recurrence, and the recurrence in 12 patients was analyzed.A case-control study was performed with the side of the parotid gland with recurrence as the case group and the side of the parotid gland without recurrence as the control group.The association of parotid gland failure with the extent of tumor invasion, IMRT dose distribution, and local recurrence was analyzed.The differences between groups were analyzed with χ2 test or Fisher′s the exact probability test.Results Among the 12 patients, 11 had stage III-IV primary NPC;after definitive IMRT, 9 had local tumor residues.The median time of parotid gland recurrence was 16(8-43) months.Of all the patients who experienced recurrence, 8 had recurrence in the superficial lobe of the parotid gland, 1 in the deep lobe, and 3 in both superficial and deep lobes.Recurrence was in the same side of primary tumor (P<0.001).Compared with the controls, the side of the parotid gland with recurrence had higher rate of cervical puncture/surgery (P=0.025).Parotid gland recurrence was often complicated by ipsilateral lymph node recurrence (67% vs.8%, P=0.003), as well as the tendency of ipsilateral primary lesion recurrence (42%vs.8%;P=0.059).Conclusions For NPC patients, the recurrence rate in the parotid gland is very low. Parotid gland recurrence may be related to locally advanced NPC, residues after treatment, the history of cervical puncture/surgery, and locoregional recurrence.The low radiotherapy dose in the parotid gland caused by IMRT may be an important reason for parotid gland recurrence.