Is elective irradiation to the lower neck necessary for N0 nasopharyngeal carcinoma?

Abstract

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 (60)Co or 6-MV X-rays, and 50-56 Gy to levels II, III, and VA. Residual disease was boosted with either (192)Ir 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 < or = 1 cm).

Conclusion: Elective levels II, III, and VA irradiation is suitable for nasopharyngeal carcinoma without neck lymph node metastasis.