Background and objective: It is controversial for the irradiation level and dose of the regional prevention for naspharyngeal cancer (NPC) with one or both cervical lymph node-negative neck. The study was to analyze the proophylactic irradiation of cervical lymph nodes for Stage -N0 NPC patients.
Methods: From January 2002 and December 2004, 205 NPC patients with negative lymphadenopathy diagnosed by imaging, were retrospectively analyzed. Before treatment, each patient underwent CT or MRI. Facial-cervical portals and 6-8 MV photons were used in radiotherapy. Doses applied were 60-80 Gy to the nasopharynx and 46-64 Gy to the neck without lymphadenopathy. Consecutive radiotherapy was performed employing conventional fractionation of 2 Gy/fraction, once a day, for a total of five fractions per week. Chemotherapy was administered to 60 patients. Median follow-up was 44 months. The survival function was calculated according to the Kaplan-Meier method. A log-rank test was used to compare the differences in survival. The Cox proportional hazards model was used for multivariate analysis. A total of 205 patients with stage-N0 NPC were divided into an upper-neck irradiation group and an entire-neck group.
Results: The 3-year overall survival rate (OS) was 92.9% and the 3-year disease-free survival rate (DFS) was 91.9%. A total of 88 patients received irradiation to the upper neck and 117 to the entire neck. The rate of regional failure for the upper-neck group and the entire-neck group were 2.27% and 0%, respectively (P>0.05). The rates of regional failure in patients with T1-, T2-, T3- and T4-stage disease were 0, 3.08%, 0, and 0, respectively (P>0.05). The rates of regional failure in the patients both without and with local failure were 1.03% and 0, respectively (P>0.05). The 1-and 3-year OS for the upper-neck group were 97.7% and 94.2%, and the 1- and 3-year OS for the entire-neck group were 97.4% and 91.9% (P=0.950). The 1- and 3-year DFS for the upper-neck group were 96.6% and 92.9%, and the 1- and 3-year DFS for the entire-neck group were 95.6% and 90.9% (P= 0.730). In multivariate analysis, sex (P=0.039) and T stage (P=0.004) were independent prognosis factors for patients with stage-N0 NPC.
Conclusions: Prophylactic irradiation to the upper neck does not influence regional failure or long-term survival in the patients with stage-N0 NPC. Radiotherapy to the upper neck (levels II, III, VA) is recommended for the patients with stage-N0 NPC. Involvement of the parapharyngeal space, T stage, and the rates of local failure do not influence regional failure in these patients. Sex and T stage were independent prognosis factors of stage-N0 NPC patients.