Table 1. Demographic and lifestyle characteristics of the head and neck cancer patients and control subjects.

Characteristics	Case N=838 n (%)	Control N=998 n (%)	P
Age (years)
Mean (SE)	55.5 (0.4)	54.7 (0.3)	0.09
Sex
Men	786 (93.8)	948 (95.0)	0.27
Women	52 (6.2)	50 (5.0)
Education
≤ Elementary school	228 (27.2)	170 (17.0)	<0.0001
Junior high	250 (29.8)	177 (17.7)
High school/Technical school	276 (33.0)	359 (36.0)
Some college or more	84 (10.0)	292 (29.3)
Alcohol drinking
Never + occasional	273 (32.6)	543 (54.4)	<0.0001
Former regular	116 (13.8)	113 (11.3)
Current regular	449 (53.6)	342 (34.3)
Never	245 (29.3)	476 (47.7)	<0.0001
1 drink or less per month	28 (3.3)	66 (6.6)
1-2 drinks per week	37 (4.4)	66 (6.6)
3-5 drinks per week	48 (5.7)	71 (7.1)
Daily drinkers	461 (55.0)	312 (31.3)
Unknown	19 (2.3)	7 (0.7)
Betel quid chewing
Never	241 (28.8)	713 (71.5)	<0.0001
Former	317 (37.8)	185 (18.5)
Current	280 (33.4)	99 (9.9)
Unknown	0 (0.0)	1 (0.1)
Never	241 (28.8)	713 (71.5)	<0.0001
0.1-9.9 pack-years	122 (14.6)	100 (10.0)
10.0-19.9 pack-years	105 (12.5)	51 (5.1)
20.0-29.9 pack-years	93 (11.1)	40 (4.0)
30.0 or more pack-years	256 (30.5)	90 (9.0)
Unknown	21 (2.5)	4 (0.4)
Pack-years (SE)	26.6 (1.3)	7.6 (0.7)	<0.0001
Cigarette smoking
Never	114 (13.6)	326 (32.7)	<0.0001
Former	158 (18.9)	205 (20.5)
Current	565 (67.4)	466 (46.7)
Unknown	1 (0.1)	1 (0.1)
Never	114 (13.6)	326 (32.7)	<0.0001
0.1-9.9 pack-years	39 (4.6)	78 (7.8)
10.0-19.9 pack-years	81 (9.7)	133 (13.3)
20.0-29.9 pack-years	140 (16.7)	128 (12.8)
30.0 or more pack-years	453 (54.1)	327 (32.8)
Unknown	11 (1.3)	6 (0.6)
Pack-years (SE)	35.8 (1.0)	23.0 (0.8)	<0.0001

Abbreviations: N: number, SE: standard error.