Stage I includes: T1, N0, M0. T1: Nasopharyngeal cancer with tumor confined to the nasopharynx, or tumor extending to oropharynx and/or nasal cavity without parapharyngeal extension. Parapharyngeal extension denotes posterolateral infiltration of tumor. N0: No regional lymph node metastasis. M0: No distant metastasis. (AJCC 7th ed.) [from
NCI]