Raw Garlic Consumption as a Protective Factor for Lung Cancer, a Population-Based Case–Control Study in a Chinese Population

Zi-Yi Jin; Ming Wu; Ren-Qiang Han; Xiao-Feng Zhang; Xu-Shan Wang; Ai-Ming Liu; Jin-Yi Zhou; Qing-Yi Lu; Zuo-Feng Zhang; Jin-Kou Zhao

doi:10.1158/1940-6207.CAPR-13-0015

DOI: 10.1158/1940-6207.CAPR-13-0015 Published July 2013

Article Figures & Data

Tables

Table 1.

Demographic information and socioeconomic status of cases and controls

Variables	Case (%; N = 1,424)	Control (%; N = 4,543)	P^a
Study area
Dafeng	625 (43.9)	2,533 (55.8)
Ganyu	799 (56.1)	2,010 (44.2)
Gender
Male	995 (69.9)	3,415 (75.2)
Female	429 (30.1)	1,128 (24.8)	<0.001
Age, y
Mean (SD)	63.3 (11.1)	64.0 (11.3)	0.037
<50	166 (11.7)	499 (11.0)
50-	328 (23.0)	989 (21.8)
60-	468 (32.9)	1,440 (31.7)
70-	387 (27.2)	1,309 (28.8)
≥80	75 (5.3)	306 (6.7)	0.173
Education level
Illiteracy	706 (49.6)	2,309 (50.8)
Primary	466 (32.7)	1,393 (30.7)
Middle	197 (13.8)	644 (14.2)
High	44 (3.1)	174 (3.8)
College	11 (0.8)	23 (0.5)	0.300
Income 10 years ago (Yuan/year)
Mean (SD)	2,260 (2170)	2,220 (2481)	0.565
<1,000	284 (19.9)	959 (21.1)
1,000-	266 (18.7)	843 (18.6)
1,500-	380 (26.7)	1,234 (27.2)
≥2500	494 (34.7)	1,507 (33.2)	0.670
BMI^b
Mean (SD)	22.2 (4.3)	22.8 (3.6)	<0.001
<18.5	204 (14.3)	307 (6.8)
18.5–23.9	862 (60.5)	2,881 (63.4)
24.0–27.9	285 (20.0)	1,103 (24.3)
≥28.0	73 (5.1)	252 (5.5)	<0.001

↵^aOn the basis of χ² testing; t testing for the mean.
↵^bChinese recommend standard was used for the cutoff points of overweight and obesity: low weight (BMI < 18.5), overweight (BMI ≥ 24.0 and BMI < 28.0), obesity (BMI ≥ 28.0).

Table 2.

The distribution of major factors and their associations with lung cancer risk

Variables	Case (%; N = 1,424)	Control (%; N = 4,543)	Crude OR (95% CI)	Adjusted OR (95% CI)^a
Ever smoking
No	394 (27.7)	1,860 (40.9)	1.00	1.00
Yes	1,030 (72.3)	2,683 (59.1)	1.81 (1.59–2.07)	2.54 (2.17–2.99)
Pack-years of smoking
Never smoker	394 (27.7)	1,860 (40.9)	1.00	1.00
<30 y	262 (18.4)	1,088 (23.9)	1.14 (0.96–1.35)	1.60 (1.32–1.94)
≥30 y	768 (53.9)	1,595 (35.1)	2.27 (1.98–2.61)	3.68 (3.08–4.40)
P_trend			<0.001	<0.001
Alcohol drinking status
Never or seldom	837(58.8)	2,782 (61.2)	1.00	1.00
Often	587(41.2)	1,761 (38.8)	1.11 (0.98–1.25)	1.04 (0.90–1.19)
Factory nearby
No	1 216 (86.7)	4,021 (89.9)	1.00	1.00
Yes	186 (13.3)	450 (10.1)	1.37 (1.14–1.64)	1.55 (1.28–1.89)
High-temperature cooking oil
No	911 (64.0)	3,194 (70.3)	1.00	1.00
Yes	513 (36.0)	1,349 (29.7)	1.33 (1.18–1.51)	1.26 (1.10–1.43)
Consumption of fried food
No	651 (45.7)	2,539 (55.9)	1.00	1.00
Yes	773 (54.3)	2,004 (44.1)	1.50 (1.34–1.70)	1.32 (1.15–1.52)
Poor ventilation in kitchen
No	558 (39.2)	1,944 (42.8)	1.00	1.00
Yes	866 (60.8)	2,599 (57.2)	1.16 (1.03–1.31)	1.12 (0.98–1.28)
Family history of lung cancer
No	1,356 (95.2)	4,433 (97.6)	1.00	1.00
Yes	68 (4.8)	110 (2.4)	2.02 (1.49–2.75)	1.98 (1.42–2.74)
Green tea drinking
No	952 (71.2)	3,028 (71.9)	1.00	1.00
Yes	386 (28.8)	1,186 (28.1)	1.04 (0.90–1.19)	0.85 (0.73–1.00)
Exercise ten years ago
No	1,111 (78.0)	3,543 (78.0)	1.00	1.00
Yes	313 (22.0)	1,000 (22.0)	1.00 (0.87–1.15)	0.82 (0.70–0.96)

↵^aAdjusted on age (continuous), gender (male = 1, female = 0), education level (illiteracy = 1, primary = 2, middle = 3, high = 4, college = 5), income (Yuan/year) 10 years ago (continuous), BMI (continuous), family history of lung cancer (yes = 1, no = 0), pack-year of smoking (continuous, except for variable of ever smoking), ethanol consumption (mL/week, continuous, except for variable of alcohol drinking status), and study area (Dafeng = 1, Ganyu = 2).

Table 3.

The association between lung cancer and raw garlic consumption frequency stratified by major factors

	Never^a	<2 times/week		≥2 times/week
Stratification variables	Case/control	Case/control	Adjusted OR (95% CI)^b	Case/control	Adjusted OR (95% CI)^b	P_trend^b
All raw garlic	704/2,423	594/1,637	0.92 (0.79–1.08)	126/483	0.56 (0.44–0.72)	<0.001
Study area
Dafeng	515/1,954	101/520	0.71 (0.56–0.92)	9/59	0.43 (0.20–0.91)	0.001
Ganyu	189/469	493/1,117	1.15 (0.94–1.42)	117/424	0.66 (0.50–0.88)	0.013
Tobacco smoking
Never smoker	194/1,095	165/591	0.95 (0.72–1.26)	35/174	0.67 (0.43–1.05)	0.137
All smokers	510/1,328	429/1,046	0.87 (0.73–1.05)	91/309	0.56 (0.42–0.74)	0.000
<30 y	129/575	119/416	0.97 (0.69–1.36)	14/97	0.42 (0.22–0.80)	0.046
≥30 y	381/753	310/630	0.86 (0.69–1.08)	77/212	0.58 (0.41–0.80)	0.002
Alcohol drinking status
Never or seldom	427/1,572	343/940	0.98 (0.80–1.19)	67/270	0.59 (0.42–0.81)	0.010
Often	277/851	251/697	0.86 (0.67–1.10)	59/213	0.56 (0.38–0.82)	0.005
Factory nearby
No	571/2,076	533/1,497	0.98 (0.83–1.16)	112/448	0.60 (0.46–0.78)	0.002
Yes	120/301	53/121	0.73 (0.45–1.17)	13/28	0.37 (0.16–0.89)	0.024
High-temperature cooking oil
No	420/1,687	410/1,169	1.02 (0.84–1.24)	81/338	0.57 (0.41–0.78)	0.006
Yes	284/736	184/468	0.80 (0.62–1.03)	45/145	0.57 (0.38–0.85)	0.004
Consumption of fried food
No	455/1,714	163/672	0.81 (0.65–1.02)	33/153	0.64 (0.41–0.98)	0.016
Yes	249/709	431/965	0.92 (0.74–1.14)	93/330	0.49 (0.36–0.67)	<0.001
Poor ventilation in kitchen
No	288/1,080	222/659	0.92 (0.72–1.18)	48/205	0.52 (0.35–0.78)	0.007
Yes	416/1,343	372/978	0.92 (0.75–1.12)	78/278	0.58 (0.42–0.79)	0.003
Family history of lung cancer
No	661/2,343	572/1,613	0.92 (0.79–1.08)	123/477	0.57 (0.44–0.73)	<0.001
Yes	43/80	22/24	1.09 (0.48–2.46)	3/6	0.26 (0.04–1.63)	0.430
Green tea drinking
No	528/1,790	358/950	0.86 (0.71–1.04)	66/288	0.44 (0.32–0.60)	<0.001
Yes	128/430	210/584	1.11 (0.83–1.50)	48/172	0.77 (0.50–1.19)	0.410
Exercise 10 years ago
No	608/2,074	410/1,148	0.84 (0.70–1.00)	93/321	0.54 (0.40–0.72)	<0.001
Yes	96/349	184/489	1.28 (0.92–1.77)	33/162	0.67 (0.41–1.10)	0.332

↵^aThe reference group.
↵^bAdjusted on age (continuous), gender (male = 1, female = 0), education level (illiteracy = 1, primary = 2, middle = 3, high = 4, college = 5), income (Yuan/year) 10 years ago (continuous), BMI (continuous), family history of lung cancer (yes = 1, no = 0, except for variable of family history of lung cancer), pack-year of smoking (continuous, except for variable of tobacco smoking), ethanol consumption (mL/week, continuous, except for variable of alcohol drinking status), and study area (Dafeng = 1, Ganyu = 2, except for variable of study area).

Table 4.

The effect modification of lung cancer risk between raw garlic consumption and major risk factors

Variables	Raw garlic consumption	Case/control	Crude OR (95% CI)	Adjusted OR (95% CI)^a
Pack-years of smoking
≥30 y	No	381/753	1.00	1.00
≥30 y	Yes^b	387/842	0.91 (0.77–1.08)	0.68 (0.56–0.83)
<30 y	No	129/575	0.44 (0.35–0.56)	0.38 (0.30–0.48)
<30 y	Yes	133/513	0.51 (0.41–0.64)	0.34 (0.26–0.43)
Never	No^c	194/1095	0.35 (0.29–0.43)	0.21 (0.17–0.27)
Never	Yes	200/765	0.52 (0.42–0.63)	0.24 (0.19–0.31)
Interaction^a	Additive:	RERI = −0.40 (95% CI, −0.60–−0.20)
		AP = −0.21 (95% CI, −0.32–−0.09)
		SI = 0.70 (95% CI, 0.57–0.85)
	Multiplicative:	ROR = 0.78 (95% CI, 0.67–0.90)
High-temperature cooking oil
Yes	No^b	284/736	1.00	1.00
Yes	Yes	229/613	0.97 (0.79–1.19)	0.74 (0.59–0.92)
No	No	420/1,687	0.65 (0.54–0.77)	0.71 (0.59–0.85)
No	Yes^c	491/1,507	0.84 (0.71–1.00)	0.68 (0.56–0.82)
Interaction^a	Additive:	RERI = 0.35 (95% CI, 0.04–0.65)
		AP = 0.23 (95% CI, 0.04–0.43)
		SI = 3.56 (95% CI, 0.42–30.46)
	Multiplicative:	ROR = 0.77 (95% CI, 0.59–1.00)
Consumption of fried food
Yes	No^b	249/709	1.00	1.00
Yes	Yes	524/1,295	1.15 (0.97–1.38)	0.91 (0.74–1.11)
No	No	455/1,714	0.76 (0.63–0.90)	0.82 (0.68–1.00)
No	Yes^c	196/825	0.68 (0.55–0.84)	0.61 (0.48–0.76)
Interaction^a	Additive:	RERI = −0.20 (95% CI, −0.59–0.18)
		AP = −0.12 (95% CI, −0.36–0.11)
		SI = 0.76 (95% CI, 0.47–1.23)
	Multiplicative:	ROR = 1.23 (95% CI, 0.94–1.61)

↵^aAdjusted on age (continuous), gender (male = 1, female = 0), education level (illiteracy = 1, primary = 2, middle = 3, high = 4, college = 5), income (Yuan/year) 10 years ago (continuous), BMI (continuous), family history of lung cancer (yes = 1, no = 0), pack-year of smoking (continuous, except for variable of ever smoking), ethanol consumption (mL/week, continuous), and study area (Dafeng = 1, Ganyu = 2).
↵^bThe joint effects category for further estimation of additive interaction.
↵^cThe reference category for measures of interaction on additive scale.