Reduction of clinical target volume in patients with lateralized cancer of the nasopharynx and without contralateral lymph node metastasis receiving intensity-modulated radiotherapy.

BACKGROUND: This study investigated lymph node distribution in patients with lateralized cancer of the nasopharynx to identify areas suitable for clinical target volume (CTV) reduction. METHODS: A total of 1680 patients with nasopharyngeal carcinoma (NPC) whose tumor involvement was assessed by MRI were reviewed retrospectively. RESULTS: One hundred and twelve patients (7%) had a lateralized primary lesion. Of these, 9 patients (8%) had contralateral lymph nodes including 4 (4%) who had contralateral cervical lymph nodes (CLNs). The rates of contralateral level III/Va metastasis were <1% (1 of 104) and 12.5% (1 of 8) in patients without and with contralateral retropharynx/level II involvement, respectively. No known risk factors were significantly associated with contralateral lymph node metastasis. CONCLUSION: Reduced cervical CTV coverage, including the contralateral level II, is feasible in patients with lateralized primary NPC, which may help to better protect the cervical OAR, including the thyroid, larynx, and esophagus. (c) 2015 Wiley Periodicals, Inc. Head Neck 38: E468-E472, 2016.