Kaplan-Meier curves for survival by different clinicopathological factors. (A) NPC patients with stage I+II disease exhibited significantly higher survival rates compared to those with stage III+IV disease. (B) and (C) NPC patients with lymph node or distant organ metastases exhibited lower survival rates compared to those without lymph node or distant organ metastasis. (D) Poor histological differentiation was associated with higher survival rates compared to high or moderate differentiation. (E), (F) and (G) NPC patients with positive expression exhibited higher survival rates compared to those with negative expression of TAP-1, TAP-2 and HLA-I. NPC, nasopharyngeal carcinoma; TAP, transporters associated with antigen processing; HLA, human leukocyte antigen; Cum, cumulative.