Table 2.

Adjusted ORs in stratified analyses

All subjects (n = 2,442, affected 502, unaffected 1,942)
EBV-positive (n = 1003, affected 502, unaffected 501)
Early age-onset (<40 y)*, (n = 1,236, affected 257, unaffected 979)
Late age-onset (≥40 y), (n = 1,206, affected 227, unaffected 963)
Families with higher no. cases (>3), (n = 841, affected 181, unaffected 660)
Families with lower no. cases (≤2), (n = 1,603, affected 321, unaffected 1,282)
VariablesCase (%)Control (%)OR (95% CI)OR (95% CI)OR (95% CI)OR (95% CI)OR (95% CI)OR (95% CI)
Duration of smoking (y)
    Never269 (58.3)1,328 (68.3)1 (reference)1 (reference)1 (reference)1 (reference)1 (reference)1 (reference)
    <20100 (21.7)385 (19.8)0.80 (0.57-1.13)0.59 (0.35-0.99)0.57 (0.36-0.91)1.41 (0.77-2.56)0.60 (0.34-1.05)0.90 (0.59-1.39)
    ≥2092 (20.0)232 (11.9)0.66 (0.45-0.96)0.58 (0.34-1.00)0.57 (0.32-1.00)0.78 (0.45-1.35)0.56 (0.29-1.05)0.67 (0.42-1.06)
Duration of betel nut (y)
    Never429 (87.0)1,759 (90.0)1 (reference)1 (reference)1 (reference)1 (reference)1 (reference)1 (reference)
    <2027 (5.5)137 (7.0)0.77 (0.46-1.28)0.62 (0.30-1.25)1.08 (0.56-2.06)0.62 (0.25-1.52)0.77 (0.35-1.70)0.70 (0.36-1.35)
    ≥2037 (7.5)59 (3.0)1.69 (0.97-2.92)1.36 (0.65-2.89)0.71 (0.27-1.84)2.44 (1.16-5.13)1.38 (0.50-3.83)1.67 (0.89-3.13)
Cumulative wood§
    None303 (93.2)1,062 (94.9)1 (reference)1 (reference)1 (reference)1 (reference)1 (reference)1 (reference)
    <257 (2.2)38 (3.4)0.54 (0.22-1.36)0.74 (0.21-2.62)0.29 (0.16-0.54)0.70 (0.20-2.49)0.33 (0.06-1.65)0.70 (0.23-2.17)
    ≥2513 (4.6)19 (1.7)2.29 (1.04-5.07)2.98 (0.93-9.51)5.10 (1.50-17.34)1.55 (0.47-5.08)4.41 (1.58-12.30)0.93 (0.23-3.75)
Guangdong salted fish (age <10) §
    Never342 (93.4)1,528 (93.4)1 (reference)1 (reference)1 (reference)1 (reference)1 (reference)1 (reference)
    <1/wk13 (3.6)72 (4.4)0.65 (0.31-1.35)0.64 (0.23-1.74)0.63 (0.26-1.57)0.32 (0.07-1.51)0.49 (0.13-1.81)0.73 (0.29-1.80)
    ≥1/wk11 (3.0)36 (2.2)1.78 (0.82-3.89)1.74 (0.58-5.20)3.94 (1.47-10.55)0.67 (0.14-3.31)4.27 (1.10-16.47)1.28 (0.48-3.39)
RSA
    c1-c157 (55.3)331 (59.9)1 (reference)1 (reference)1 (reference)1 (reference)1 (reference)1 (reference)
    c1/2-c246 (44.7)222 (40.1)1.45 (0.79-2.65)0.81 (0.35-1.85)0.81 (0.43-1.54)1.62 (0.47-5.62)0.42 (0.15-1.21)2.06 (1.04-3.35)
  • * At least one affected individual in that family had early age-onset.

  • No. cases in a family was based on the total number of affected subjects, regardless of how many were recruited in that family.

  • Total years of exposure before diagnosis.

  • § Occupational and dietary data were available for 59% (65% cases and 57% controls) and 89% (82% cases and 91% controls) subjects, respectively.

  • The interaction was statistically significant between genetic risk (defined as having three or more cases within a family) and heavy wood exposure (P = 0.018), but was not significant with frequent fish consumption (P = 0.23). Interactions were tested by including an interaction term in the model.

  • Combined c1-c2 and c2-c2 genotype. Genotyping results were available on 103 affected (21%) and 553 (28%) unaffected individuals. Adjusted for age, sex, cigarette smoking, betel nut consumption, wood and formaldehyde exposure, and Guangdong and other salted fish consumption during childhood.