Table 1. Distributions of select characteristics by cases and controls subjects.

Variables	Case (n = 706)		Controls (n = 706)		P valuea
	No	(%)	No	(%)
Sex					0.87
Male	471	66.7	474	67.1
Female	235	33.3	232	32.9
Age					1.00
≤ 50	125	17.7	125	17.7
51–60	265	37.5	265	37.5
61–70	226	32.0	226	32.0
> 70	90	12.7	90	12.7
Smoking status					0.00
Non-smoker	390	55.2	506	71.7
Smoker	316	44.8	200	28.3
Pack-year smoked					0.74
≤ 30	188	59.5	116	58.0
> 30	128	40.5	84	42.0
Histological types
Adenocarcinoma	404	57.2
Squamous cell	273	38.7
Other carcinomas	29	4.1

^aTwo-sided χ² test.