Table 2.
Association of IL-6 and IL-8 serum levels with lung cancer in the NCI-MD study, and lung cancer risk in the PLCO study*
| NCI-MD Study |
PLCO Study |
|||||
| Cytokine level | No. of case patients/No. of control subjects | OR (95% CI)† | Adjusted OR (95% CI)‡ | No. of case patients/No. of control subjects | OR (95% CI)† | Adjusted OR (95% CI)‡ |
| IL-6 | ||||||
| First quartile§ | 27/73 | 1.00 (referent) | 1.00 (referent) | 107/149 | 1.00 (referent) | 1.00 (referent) |
| Second quartile | 30/75 | 1.08 (0.59 to 1.99) | 0.98 (0.51 to 1.86) | 112/138 | 1.22 (0.87 to 1.72) | 1.14 (0.79 to 1.65) |
| Third quartile | 83/74 | 3.03 (1.76 to 5.21) | 2.28 (1.29 to 4.06) | 147/158 | 1.36 (0.96 to 1.93) | 1.25 (0.88 to 1.78) |
| Fourth quartile | 130/74 | 4.75 (2.81 to 8.03) | 3.29 (1.88 to 5.77) | 166/150 | 1.55 (1.10 to 2.19) | 1.48 (1.04 to 2.10) |
| Ptrend | 3.5 × 10−12 | 3.6 × 10−7 | .01 | .02 | ||
| Low IL-6¶ | 57/148 | 1.00 (referent) | 1.00 (referent) | 237/304 | 1.00 (referent) | 1.00 (referent) |
| High IL-6 | 213/148 | 3.74 (2.58 to 5.41) | 2.82 (1.90 to 4.20) | 295/291 | 1.30 (1.03 to 1.64) | 1.26 (1.00 to 1.61) |
| P | 3.0 × 10−7‖ | 3.0 × 10−7‖ | .03‖ | .05‖ | ||
| IL-8 | ||||||
| First quartile§ | 34/74 | 1.00 (referent) | 1.00 (referent) | 102/147 | 1.00 (referent) | 1.00 (referent) |
| Second quartile | 57/74 | 1.68 (0.98 to 2.86) | 1.48 (0.84 to 2.63) | 114/153 | 1.07 (0.76 to 1.52) | 1.03 (0.72 to 1.48) |
| Third quartile | 96/74 | 2.82 (1.70 to 4.69) | 2.62 (1.52 to 4.51) | 148/147 | 1.43 (1.01 to 2.01) | 1.41 (0.99 to 2.01) |
| Fourth quartile | 83/74 | 2.44 (1.46 to 4.08) | 2.06 (1.19 to 3.57) | 169/147 | 1.66 (1.18 to 2.32) | 1.57 (1.10 to 2.24) |
| P | 2.0 × 10−4‖ | .003‖ | .001‖ | .003‖ | ||
| Low IL-8¶ | 91/148 | 1.00 (referent) | 1.00 (referent) | 219/306 | 1.00 (referent) | 1.00 (referent) |
| High IL-8 | 179/148 | 1.97 (1.40 to 2.76) | 1.86 (1.29 to 2.68) | 323/300 | 1.49 (1.17 to 1.88) | 1.47 (1.15 to 1.88) |
| P | 9.6 × 10−5‖ | .001‖ | .001‖ | .002‖ | ||
CI = confidence interval; IL-6 = interleukin 6; IL-8 = interleukin 8; NCI-MD = National Cancer Institute-Maryland study; PLCO = Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial; OR = odds ratio.
Univariate analysis; analysis was done by unconditional logistic regression.
Multivariable unconditional logistic regression analysis adjusted for age (continuous), sex, smoking pack-years (continuous), smoking status (never, former quit ≤15 years, former quit >15 years, and current), PLCO study adjusted additionally for year of randomization and number of years in the study.
Quartiles were based on serum IL-6 and IL-8 cutoff levels among controls in NCI-MD study (25th, 50th, and 75th percentile: IL-6, 1.4, 2.1, 3.8 pg/mL, respectively; IL-8, 7.0, 10.8 and 28.5 pg/mL, respectively) and PLCO study (IL-6, 2.7, 4.0, 6.6 pg/mL, respectively; IL-8, 13.1, 17.4, 23.3 pg/mL, respectively).
Serum IL-6 and IL-8 levels were dichotomized (≤median vs >median) among control subjects in the NCI-MD (IL-6 2.1 pg/mL; IL-8 10.8 pg/mL) and PLCO (IL-6, 4.0 pg/mL; IL-8, 17.4 pg/mL) studies.
P values were calculated using a two-sided Wald χ2 statistic.