Table 1.

Frequency distribution of selected characteristics of study subjects by the case-control status

VariableCases (n = 373)
Controls (n = 365)
No. (%)*No. (%)*
Age (y)
    ≤45142 (38.1)143 (39.2)
    >45231 (61.9)222 (60.8)
Gender
    Male212 (56.8)159 (43.6)
    Female161 (43.2)206 (56.4)
Smoking status
    Never222 (59.7)205 (56.2)
    Ever150 (40.3)160 (43.8)
Family history of brain tumor
    No339 (96.0)326 (97.3)
    Yes14 (4.0)9 (2.7)
IR exposure history
    No337 (90.6)337 (94.1)
    Yes35 (9.4)21 (5.9)
Histology type
    High grade214 (57.4)
    Medium grade77 (20.6)
    Low grade82 (22.0)
  • Abbreviation: IR, ionizing radiation.

  • * Numbers do not add up to the column totals because of missing values.

  • High-grade glioma (glioblastoma); medium-grade glioma (anaplastic astrocytoma); low-grade glioma (oligodendroglioma, not-otherwise-specified astrocytoma, and mixed glioma).