Table 1

 Distributions of selected characteristics by case−control status

VariableNPC patients (n = 239)Controls (n = 286)
*p<0.01, compared with controls; †ohers include poorly differentiated adenocarcinoma (n = 8), higher differentiated squamous cell carcinoma (n = 6),and undifferentiated cancer (n = 9).
Sex (%)
    Male163 (68.2)*151 (52.8)
    Female76 (31.8)*135 (47.2)
Mean (SD) age (years)46.9 (11.2)47.2 (12.8)
Histological type (%)
    Poorly differentiated squamous cell carcinoma216 (90.4)
    Others†23 (9.6)