Table 2.
Distribution of selected characteristics and DNA Repair score* between non–small cell lung cancer case patients and control individuals
| Control individuals (n = 140) |
Case patients (n = 149) |
||||
|---|---|---|---|---|---|
| Characteristics | No. | DNA Repair score mean (95% CI) | P | No. | DNA Repair score mean (95% CI) |
| All† | 140 | 4.00 (3.84 to 4.16) | 149 | 2.67 (2.50 to 2.84) | |
| P Case vs control‡ < .001 | |||||
| Histology | |||||
| SQCC | – | – | 56 | 2.69 (2.45 to 2.93) | |
| Adenocarcinoma | – | – | 82 | 2.62 (2.38 to 2.86) | |
| Unknown | – | – | 11 | 2.92 (1.87 to 3.98) | |
| P SQCC vs adenocarcinoma§ = .65 | |||||
| Age, y | |||||
| ≤55 | 43 | 4.28 (3.96 to 4.59) | 16 | 2.36 (1.82 to 2.89) | |
| 56–69 | 75 | 4.00 (3.81 to 4.20) | 64 | 2.86 (2.55 to 3.16) | |
| ≥70 | 22 | 3.45 (2.95 to 3.94) | 69 | 2.56 (2.35 to 2.78) | |
| P Age trend‖ = .075 | |||||
| Sex | |||||
| Male | 77 | 3.82 (3.59 to 4.05) | 93 | 2.71 (2.49 to 2.93) | |
| Female | 63 | 4.21 (3.99 to 4.44) | 56 | 2.60 (2.32 to 2.88) | |
| P M vs F‖ = .47 | |||||
| Smoking status | |||||
| Never smoked | 45 | 4.07 (3.79 to 4.36) | 1 | 4.85 | |
| Past smoker | 49 | 3.98 (3.72 to 4.24) | 87 | 2.60 (2.40 to 2.81) | |
| Current smoker | 46 | 3.95 (3.62 to 4.27) | 61 | 2.72 (2.43 to 3.02) | |
| P Ever-smoked vs never smoked‖ = .32; | |||||
| P Current smoker vs others‖ = .65 | |||||
| COPD | |||||
| No | 109 | 4.02 (3.85 to 4.19) | 56 | 2.86 (2.55 to 3.18) | |
| Yes | 22 | 3.82 (3.30 to 4.34) | 77 | 2.57 (2.35 to 2.79) | |
| P Yes vs no¶ = .13 | |||||
The DNA Repair score was defined as: 0.00621 × APE1 − 0.047 × OGG1 − 0.0223 × MPG, where APE1, OGG1, and MPG each represent the measured enzyme activity of an individual. The weights for each component used in the DNA Repair score were calculated from the logistic regression and chosen to optimize strength of association of the score with lung cancer for the observed data set. APE1 = apurinic/apyrimidinic endonuclease 1; CI = confidence interval; COPD = chronic obstructive pulmonary disease; MPG = methylpurine DNA glycosylase; OGG1 = 8-oxoguanine DNA glycosylase; SQCC = squamous cell carcinoma.
Values were missing for three control individuals (two current and one past smoker) and one case patient (current smoker).
Two-sided P value comparing the distribution of case patients with control individuals: analysis of covariance was used adjusting the comparison for continuous age, sex, and smoking status.
Two-sided P value for comparing SQCC with adenocarcinoma: analysis of covariance was used adjusting for case-control-status, continuous age, sex, and smoking status.
Two-sided P values obtained from analysis of covariance for factor of interest, adjusted for case-control status and other factors from among age, sex, and smoking status.
Two-sided P value comparing COPD vs no COPD; using analysis of covariance adjusting for continuous age and sex.