Soyfood Intake during Adolescence and Subsequent Risk of Breast Cancer among Chinese Women

Xiao Ou Shu; Fan Jin; Qi Dai; Wanqing Wen; John D. Potter; Lawrence H. Kushi; Zhixian Ruan; Yu-Tang Gao; Wei Zheng

DOI: Published May 2001

Article Figures & Data

Tables

Table 1

Comparison of demographics and selected breast cancer risk factors of cases and controls, The Shanghai Breast Cancer Study, 1996–1998

Subjects with missing values were excluded from the analysis.
	Cases^a (n = 1459)	Controls^a (n = 1556)	P
Age (yrs)	47.8 ± 8.0	47.2 ± 8.8	0.03
Education (%)
No formaleducation	3.6	5.5
Elementary school	8.5	8.4
Middle + high school	74.3	75.4
Professional education, college and above	13.6	10.7	0.01
Per capita income (Yuan) (%)
<4000	19.8	18.2
4000–5999	31.7	31.9
6000–7999	13.0	13.9
8000–8999	20.2	23.5
≥9000	15.2	12.4	0.05
Breast cancer in first-degree relatives (%)	3.7	2.4	0.05
Ever had breast fibroadenoma (%)	9.6	5.0	<0.01
Regular alcohol drinker (%)	4.0	4.1	0.99
Ever used oral contraceptives (%)	21.9	20.9	0.51
Ever used hormone replacement therapy (%)	2.9	2.7	0.76
Exercised regularly (%)	18.8	25.2	<0.01
Body mass index	23.5 ± 3.4	23.1 ± 3.4	<0.01
WHR	0.81 ± 0.06	0.80 ± 0.06	<0.01
Nulliparous (%)	5.1	3.9	0.13
No. of live births^b	1.5 ± 0.85	1.5 ± 0.86	0.54
Age at first live birth^b (yrs)	26.8 ± 4.2	26.2 ± 3.9	<0.01
Months of breastfeeding^c	15.1 ± 13.1	15.9 ± 14.0	0.81
Menarcheal age (yrs)	14.5 ± 1.6	14.7 ± 1.7	<0.01
Menopausal age^d (yrs)	48.1 ± 4.6	47.5 ± 4.9	0.02
Height (cm)	158.9 ± 5.10	158.5 ± 5.37	0.07
Adult usual energy intake (kcal/day)	1865.9 ± 464.2	1839.9 ± 464.2	0.12
Adult usual fat intake (grams/day)	36.3 ± 17.4	35.3 ± 16.2	0.08

^a Unless otherwise specified, mean ± SD are presented.
^b Among women who had live births.
^c Among women who ever breastfed their children.
^d Among menopausal women.

Table 2

Soy food and other dietary intake during adolescence and risk of breast cancer, The Shanghai Breast Cancer Study, 1996–1998

	Median intake among controls^a	Adjusted ORs (95% CI) by quintile^b^,c^,d							Trend test P
	Median intake among controls^a			Q1 (low)	Q2	Q3	Q4	Q5	Trend test P
Soy foods (total)	5.4	1.00	0.75 (0.60–0.93)	0.69 (0.55–0.87)	0.69 (0.55–0.86)	0.51 (0.40–0.65)	<0.01
Bean curd (tofu)	0.9	1.00	0.83 (0.68–1.02)	0.88 (0.68–1.13)	0.67 (0.54–0.84)	0.70 (0.55–0.90)	<0.01
Soy milk	0	1.00	0.75 (0.64–0.88)				<0.01
Soy products other than tofu	3.5	1.00	0.85 (0.67–1.08)	0.79 (0.59–1.06)	0.65 (0.50–0.85)		<0.01
Fresh legumes^e	35.6	1.00	0.95 (0.74–1.22)	0.98 (0.80–1.19)	0.83 (0.65–1.05)	0.93 (0.74–1.16)	0.27
Dried beans^f	0.7	1.00	0.84 (0.69–1.01)	0.78 (0.64–0.96)	0.75 (0.59–0.95)		<0.01
Vegetables/fruits (total)^g	171.0	1.00	0.88 (0.70–1.12)	0.85 (0.67–1.08)	1.01 (0.81–1.27)	0.95 (0.74–1.21)	0.97
Vegetables^g	150.0	1.00	0.87 (0.72–1.06)	0.90 (0.68–1.19)	1.17 (0.96–1.43)	0.72 (0.50–1.03)	0.56
Fruits^g	4.9	1.00	0.90 (0.74–1.10)	0.97 (0.78–1.22)	0.99 (0.79–1.23)		0.96
Rice/wheat products^g	400.0	1.00	0.95 (0.71–1.29)	0.96 (0.78–1.18)	0.86 (0.71–1.04)	0.65 (0.46–0.93)	0.03
Meats (total)^g	14.2	1.00	0.94 (0.74–1.19)	1.11 (0.87–1.41)	1.00 (0.78–1.27)	1.00 (0.78–1.29)	0.83
Pork^g	8.2	1.00	1.08 (0.84–1.38)	1.15 (0.93–1.41)	1.00 (0.78–1.29)	1.11 (0.88–1.41)	0.46
Other meats^g	1.4	1.00	0.92 (0.75–1.12)	0.96 (0.76–1.21)	0.91 (0.74–1.13)		0.51
Eggs^g	9.9	1.00	1.00 (0.80–1.25)	1.01 (0.81–1.26)	0.98 (0.78–1.24)	0.86 (0.67–1.11)	0.34
Seafoods^g	14.2	1.00	0.86 (0.68–1.08)	0.86 (0.67–1.10)	0.89 (0.71–1.12)	0.89 (0.67–1.17)	0.47
Milk^g	0	1.00	0.76 (0.59–0.98)				0.03
Preserved foods (total)^g	19.2	1.00	1.08 (0.86–1.36)	1.05(0.83–1.32)	0.89(0.70–1.13)	0.94 (0.73–1.20)	0.27
Preserved meat/fish^g	0.7	1.00	1.01 (0.83–1.24)	1.24 (1.01–1.53)	1.12 (0.90–1.38)		0.10
Salted eggs^g	1.4	1.00	0.77 (0.63–0.95)	1.00 (0.80–1.23)	1.00 (0.80–1.24)		0.62
Preserved vegetables^g	14.2	1.00	1.17 (0.93–1.47)	1.08 (0.87–1.35)	0.89 (0.70–1.12)	0.97 (0.73–1.28)	0.24

^a Average daily intake in grams. Soy food intake was converted to soy protein equivalence (tofu, 6.2%; soy milk, 1.8%; and soy products other than tofu, 24.72%); Refs. 33 34 35 .
^b ORs were compared to the lowest quintile of intake and adjusted for intake level of rice and wheat products, age, education, family history of breast cancer, history of breast fibroadenoma, WHR, age at menarche, physical activity, ever had live birth, age at first live birth, menopausal status, and age at menopause. Quintile cutoffs are 0.44, 0.88, 1.32, and 2.2 gram(s)/day for tofu and 2.20, 4.41, 6.61, and 11.01 gram(s)/day for total soyfoods.
^c Ever versus never for analyses of foods rarely consumed.
^d Tertile distribution of intake for analyses of foods when a large number of subjects did not eat the foods. Tertile cutoffs are 3.52 and 5.28 grams/day for soy products other than tofu.
^e Commonly consumed fresh legumes include peas, string beans, and kidney beans, and, less commonly consumed legumes include soy beans.
^f Commonly consumed dry beans are soy bean seeds, mung beans, and red beans.
^g Additionally adjusted for total soy food intake.

Table 3

Soy food and other dietary intake during adolescence and risk of breast cancer, The Shanghai Breast Cancer Study, 1996–1998

	Adjusted ORs (95% CI) by quintile^a^,b^,c						Trend test P
		Q1 (low)	Q2	Q3	Q4	Q5	Trend test P
A. Premenopausal women (952 cases and 990 controls)
Soy foods (total)	1.00	0.75 (0.57–1.00)	0.72 (0.54–0.96)	0.64 (0.48–0.85)	0.53 (0.39–0.72)	<0.01
Bean curd (tofu)	1.00	0.73 (0.56–0.92)	0.87 (0.64–1.20)	0.60 (0.45–0.79)	0.79 (0.58–1.08)	0.02
Soy milk	1.00	0.67 (0.55–0.82)				<0.01
Soy products other than tofu	1.00	0.90 (0.65–1.23)	0.76 (0.52–1.10)	0.68 (0.48–0.96)		0.01
Fresh legumes^d	1.00	1.04 (0.76–1.41)	1.04 (0.82–1.33)	0.86 (0.64–1.15)	0.96 (0.72–1.29)	0.51
Dried beans^e	1.00	0.91 (0.72–1.15)	0.85 (0.66–1.10)	0.77 (0.57–1.05)		0.07
B. Postmenopausal women (501 cases and 562 controls)
Soy foods (total)	1.00	0.69 (0.48–1.01)	0.65 (0.44–0.97)	0.79 (0.54–1.16)	0.49 (0.33–0.74)	<0.01
Bean curd (tofu)	1.00	1.10 (0.77–1.57)	0.89 (0.58–1.38)	0.82 (0.56–1.19)	0.62 (0.41–0.93)	0.01
Soy milk	1.00	0.98 (0.73–1.32)				0.89
Soy products other than tofu	1.00	0.77 (0.53–1.12)	0.93 (0.57–1.53)	0.62 (0.41–0.94)		0.05
Fresh legumes^d	1.00	0.77 (0.50–1.19)	0.92 (0.65–1.30)	0.83 (0.55–1.27)	0.96 (0.67–1.39)	0.82
Dried beans^e	1.00	0.70 (0.50–0.97)	0.67 (0.46–0.95)	0.76 (0.53–1.08)		0.03
C. Data reported by mothers among women <40 years of age (296 cases and 359 controls)
Soy foods (total)	1.00	0.70 (0.45–1.09)	0.59 (0.32–1.07)	0.60 (0.37–0.99)	0.35 (0.21–0.60)	<0.01
Bean curd (tofu)	1.00	1.08 (0.70–1.65)	0.72 (0.41–1.27)	0.52 (0.31–0.85)	0.65 (0.37–1.17)	<0.01
Soy milk	1.00	0.89 (0.61–1.31)				0.56
Soy products other than tofu	1.00	1.10 (0.67–1.79)	0.72 (0.45–1.17)	0.79 (0.46–1.33)	0.44 (0.25–0.79)	<0.01
Fresh legumes^d	1.00	0.52 (0.30–0.92)	0.88 (0.57–1.38)	1.05 (0.63–1.75)	0.67 (0.40–1.12)	0.55
Dried beans^e	1.00	0.94 (0.62–1.44)	0.73 (0.46–1.16)	0.63 (0.40–1.01)		0.04

^a ORs were compared to the lowest quintile of intake and adjusted for intake level of rice and wheat products, age, education, family history of breast cancer, history of breast fibroadenoma, WHR, age at menarche, physical activity, ever had live birth, menopausal status, and age at menopause.
^b Ever versus never for analyses of foods rarely consumed.
^c Tertile distribution of intake for analyses of foods when a large number of subjects did not eat the foods.
^d Commonly consumed fresh legumes include peas, string beans, kidney beans, and, less commonly consumed fresh legumes include soy beans.
^e Commonly consumed dry beans are soy bean seeds, mung beans, and red beans.