A Prospective Randomized Study Of Different Radiotherapy On Neck For N₀Nasopharyngeal Carcinoma: Upper Versus Whole Neck Prophylactic Irradiation

BACKGROUND&OBJACTIVE:The volume to be irradiated during electiveneck irradiation for patients with node negative nasopharyngeal carcinoma（N₀NPC）remains controversial.This prospective study was to analyze and compare long-termoutcomes of the N₀NPC patients treated by prophylactic irradiation to the upper neckand to the whole neck,and explore appropriate extent for elective irradiation to the N₀NPC patients,then providing reasons for formulating rational treatment scheme.METHODS:From November2005to May2011,177N₀-NPC patients,who werediagnosed by pathology and imageology.These patients were randomly assigned toeither upper neck prophylactic irradiation or whole neck prophylactic irradiation.ofthe177patients,88received prophylactic irradiation to the upper neck（upper neckgroup）,other89to the whole neck（whole neck group）.Patients in both groups wasgiven70Gy to the primary tumor and50Gy to the upper neck node area in convent-ional fraction,and patients in whole neck irradiation group also received50Gy to thelower neck region.The division of the upper and lower neck was set at the inferioredge of the cricoid bone. Kaplan-Meier method and log-rank test were used toanalyze and compare overall survival rate、disease-free survival rate、distant failure-free rate and local failure-free rate of the two groups. Cox-model was used to studyprognostic factors of N₀NPC.RESULTS:The median follow-up period was32（6-75）months.The2-,3-,4-yearoverall survival rate for the whole group were92.4%、89.0%、83.8%. The2-,3-,4-year disease-free survival rates for the whole group were85.0%、80.7%、77.7%.The2-,3-,4-year overall survival rates were92.2%、90.5%、85.0%in upper neckgroup and92.7%、87.8%、82.7%in whole neck group（P=0.336）.The2-,3-,4-yeardisease-free survival rates were86.1%、81.3%、78.4%in upper neck group, and84.0%,80.0%,76.8%in whole neck group （P=0.553）.23patients died during thefollow-up period,and the main causes of death were distant metastases and local relapse. There was no cervical lymph node relapse in the two groups,but two patientssuspiciously nodal relapsed. Univariate and Multivariate analysis showed that onlyT-stage was significant prognosis factors of N₀-NPC patients for predicting overallsurvival.CONCLUSIONS:Prophylactic irradiation to upper neck（levels Ⅱ、Ⅲ、Ⅴ_A）issuitable and recommended for N0-NPC patients.