Table 2.

The inclusion criteria and exclusion criteria for the patients with NPC

Inclusion criteria	Exclusion criteria
Biopsy-proven, WHO II or III NPC	WHO I NPC or other pathological types
Patients first diagnosed in Sun Yat-Sen University Cancer Center	Patients first diagnosed in another hospital
Patients without any treatment, including radiotherapy, chemotherapy, and surgery	Patients treated by radiotherapy, chemotherapy, and surgery
No second primary tumors	Patients with other tumours