CLDN9 and nasopharyngeal carcinoma: Moreover, the expression of claudin-9 was not related to age (P = 1.000), histological grade (P = 1.000), expression of Ki67 (P = 0.486), lymph node metastasis (P = 1.000) and clinical staging (P = 0.162) (Table 2), these data revealed that claudin-9 expression in nasopharyngeal carcinoma was not noticeably different from that in non-neoplastic mucosa.