Is Elective Irradiation to the Lower Neck Necessary for N0 Nasopharyngeal Carcinoma?

Purpose To summarize our experience and treatment results in lymph node–negative nasopharyngeal carcinoma treated in a single institution. Methods and Materials From January 2000 to December 2003, 410 patients with lymph node–negative nasopharyngeal carcinoma were retrospectively analyzed. The T-stage distribution was 18.8% in T1, 54.6% in T2 (T2a, 41 patients; T2b, 183 patients), 13.2% in T3, and 13.4% in T4. All patients received radiotherapy to the nasopharynx, skull base, and upper neck drainage areas, including levels II, III, and VA. The dose was 64–74 Gy, 1. 8–2.0 Gy per fraction over 6.5–7.5 weeks to the primary tumor with 60Co or 6-MV X-rays, and 50–56 Gy to levels II, III, and VA. Residual disease was boosted with either 192Ir afterloading brachytherapy or small external beam fields. Results The median follow-up time was 54 months (range, 3–90 months). Four patients developed neck recurrence, and only 1 patient (0.2%) experienced relapse outside the irradiation fields. The 5-year overall survival rate was 84.2%. The 5-year relapse-free survival rate, distant metastasis-free survival rate, and disease-free survival rate were 88.6%, 90.6% and 80.1%, respectively. Both univariate and multivariate analyses demonstrated that T classification was the only significant prognostic factor for predicting overall survival. The observed serious late toxicities were radiation-induced brain damage (7 cases), cranial nerve palsy (16 cases), and severe trismus (13 cases; the distance between the incisors was ≤1 cm). Conclusion Elective levels II, III, and VA irradiation is suitable for nasopharyngeal carcinoma without neck lymph node metastasis.