Etiological analysis of the sequelae of radiotherapy for nasopharyngeal carcinoma: a follow-up study of 112 cases.

OBJECTIVE: To explore the etiology of the sequelae of radiotherapy for nasopharyngeal carcinoma (NPC) so as to find the possible means for reducing or preventing its occurrence. METHODS: A total of 112 pathologically confirmed patients with nasopharyngeal carcinoma, who had survived for 5 years following the radiotherapy, were included in this study. Sixty-four patients with the primary carcinoma in the nasopharyngeal region received radiotherapy with the radiation field covering the bilateral anterior ear regions, and in the other 48 patients, adjuvent exposure of the anterior nasal region was administered. The metastases in the cervical lymph nodes were exposed to tangential radiation by 40 Gy X-ray followed by approximately 20 Gy vertical electron beam exposure. RESULTS: Limited mouth-opening and dry mouth occurred mostly during the first 2 years after radiotherapy, and hearing loss in the first year. Neck fibrosis tended to increase with the time elapse after the therapy, and posterior cranial nerve damages showed no signs of time-related occurrence. It was found that the occurrence of neck fibrosis, dry mouth and the nerve injuries did not obviously correlate with the dosage of X-ray exposure in the anterior ear regions, while limited mouth-opening and the hearing loss increased with the radiation dosage. The sequelae did not arise from different radiation field selection as adopted in this study. CONCLUSION: The radiation dose should be controlled at around 70 Gy for NPC treatment, and for carcinoma remnant in the nasopharyngeal region, additional dose in the cavity would be appropriate. When the X-ray dose of 65 Gy in the neck region fails to result in satisfactory recession of lymph node metastasis, comprehensive treatment involving multiple modalities should be considered.