Table 1.

Distribution of selected characteristics and APE1 activity value in lung cancer patients and control subjects^a

Variable	Control subjects (n = 100)		Case patients (n = 100)		P
	No.	APE1 mean (95% CI)	No.	APE1 mean (95% CI)
Allb	99	793 (751–834)	99	691 (655–727)	0.0006c
SQCC			30	656 (598–713)
Adenocarcinoma			45	689 (643–735)
P comparing subgroupsd					0.43
P interactione					0.99
Age, y
≤65	40	844 (781–907)	40	713 (655–771)
>65	59	758 (705–812)	59	676 (631–722)
P comparing subgroupsf					0.009
P interactione					0.54
Sex
Male	59	749 (711–788)	59	684 (642–725)
Female	40	857 (774–940)	40	702 (637–767)
P comparing subgroupsf					0.041
P interactione					0.055
Smoking status
Never smoked	50	819 (753–885)	24	704 (634–775)
Past smoker	27	768 (700–837)	36	702 (637–767)
Current smoker	22	765 (691–839)	36	664 (618–711)
P comparing subgroupsf					0.16
P interactione					0.72

^aAPE1 activity was measured as described in the ‘Materials and methods’. One participant did not have a known APE1 value. This participant and the matched controls were excluded from the analysis. Three case participants did not have a known smoking status.

^bOf the 100 lung cancer cases, 30 had squamous cell carcinoma (SQCC), 46 had adenocarcinoma, 14 BAC, 4 adenosquamous carcinoma, 4 adenoBAC; 1 small cell carcinoma and 1 unknown histology.

^cAnalysis of covariance comparing cases with controls, with matched pair and smoking status as a covariate.

^dAnalysis of covariance comparing histological type within cases, with smoking status, age (continuous) or gender as covariates.

^eTest for interaction between case–control status and the variable of interest.

^fAnalysis of covariance comparing subsets defined by the variable of interest and stratified by cases and controls, with smoking status, age (continuous) or gender as covariates, as appropriate.