Table 2.

Incidence and adjusted hazard ratio (95% CI) of developing nasopharyngeal carcinoma by seromarkers of antibodies against EBV at study entry

VariableParticipant number (%)Person-yearsNasopharyngeal carcinoma
Case no.Incidence rate*Hazard ratio (95% CI)
Anti–EBV VCA IgA (titer)
    Seronegative (<1:10)9,460 (98.9)171,052.52715.81.0 (reference)
    1:1087 (0.9)1,333.92149.99.5 (2.2-40.1)
    ≥1:4022 (0.2)316.32632.321.4 (2.8-161.7)
    Missing531,002.9199.7
    P value for trend<0.0001
Anti–EBV DNase (unit)
    Seronegative (<2)8,420 (88.0)152,853.82315.01.0 (reference)
    2-51,032 (10.8)18,000.7422.21.6 (0.5-4.6)
    ≥6116 (1.2)1,833.64218.216.0 (5.4-47.1)
    Missing541,017.5198.3
    Pvalue for trend<0.0001
Combination of VCA IgA/DNase
    <1:10 and <28,357 (87.3)151,867.22113.81.0 (reference)
    1:10 and/or 2-51,078 (11.3)18,748.4421.31.6 (0.5-4.7)
    ≥1:40 or ≥6132 (1.4)2,050.26292.719.0 (7.0-51.5)
    Missing551,039.8196.2
    P value for trend<0.0001
  • Abbreviation: IgA, immunoglobulin A; VCA, viral capsid antigen.

  • * Per 100,000 person-years.

  • Adjustment for age and cumulative exposure to cigarette smoking (pack-years).

  • P < 0.01.