This summary table contains detailed information about research studies. While viewing summary tables offers an informative glimpse at the science behind many breast cancer guidelines and recommendations, they should be viewed with some caution. There are a number of concepts you must understand to be able to successfully read and interpret research tables. To get some background information about understanding research tables, please see How to Read a Research Table.
|
Introduction: Although a number of case-control studies have suggested that soy products may offer some protection against breast cancer, large prospective cohort studies have been less consistent. As a result, the potential benefit of a high soy intake on breast cancer risk remains unclear. The topic, however, is being actively studied.
Find more information on the strengths and weaknesses of different types of studies.
See how this risk factor compares with other risk factors for breast cancer.
Study selection criteria: Available prospective cohort studies and case-control with at least 300 breast cancer cases.
Table note: Relative risk above 1 indicates increased risk. Relative risk below 1 indicates decreased risk.
Study
|
Study Population
(number of participants)
|
Type of Soy Intake
(categories compared)
|
Relative Risk of Breast Cancer in Women with High versus Low Intake of Soy Products,
RR (95% CI)
|
Prospective cohort studies
|
| Wu et al. [1] |
35,303
(629 cases)
|
Total soy intake:
High vs. Low
|
0.82
(0.70-0.97)
|
| Lee et al. [2] |
73,223
(592 cases) |
Soy protein intake in adulthood:
>=12.8 vs. <=4.9 g/day
|
All women:
0.89
(0.66-1.15)
Premenopausal:
0.41
(0.25-0.70)
Postmenopausal:
1.22
(0.87-1.71)
|
| |
|
Soy protein intake in adolescence:
>=11.3 vs. <=2.8 g/day
|
All women:
0.97
(0.75-1.27)
Premenopausal:
0.57
(0.34-0.97)
Postmenopausal:
1.20
(0.87-1.65)
|
Travis et al. [3]
|
37,643
(585 cases)
|
Soy food plus soy milk intake:
>20 mg/day vs. <10 mg/day
|
1.17
(0.79-1.71) |
| Key et al. [4] |
34,759
(427 cases)
|
Tofu intake:
≥5 times/week vs.
≤1 times/week
|
1.07
(0.78-1.47)
|
| |
|
Miso soup intake:
≥5/week vs. None
|
0.87
(0.68-1.120)
|
| |
|
Total intake of miso soup and tofu:
High vs. Low |
0.94
(0.73-1.20)
|
| Yamamoto et al. [5] |
21,582
(179 cases)
|
Soy-based food intake:
Almost daily vs.
<2 times/week
|
0.81
(0.49-1.30) |
Nishio et al. [6]
|
30,454
(145 cases)
|
Tofu intake:
Almost daily vs.
<3 times/week
|
1.14
(0.74-1.77)*
|
| |
|
Miso soup intake:
>=2 cups/day vs.
<1 cup/day
|
1.01
(0.65-1.56)*
|
Case-control studies
|
| |
Cases
|
Controls
|
|
|
Sanderson et al. [7]
|
1,459
|
1,556
|
Soy-based food intake:
>12.22 vs.
<6.96 grams/day
|
1.0 (0.7-1.5)
|
Horn-Ross et al. [8]
|
1,326
|
1,657
|
Soy milk intake:
Any vs. None
|
0.57
(0.38-0.85)
|
| |
|
|
Miso soup intake:
≥1 serving/month vs.
None
|
1.1
(0.81-1.50)
|
Hirose et al. [9]
|
1,186
|
21,295
|
Miso soup intake:
Daily vs.
Less than daily
|
1.2
(1.0-1.4)†
|
| |
|
|
Tofu intake:
≥3 times/week vs.
≤3 times/month
|
0.78
(0.60-1.00)†
|
Yuan et al. [10]
|
834
|
834
|
Total soy intake:
High vs. Low
|
1.0
(0.7-1.4)
|
| Suzuki et al. [11] |
678 |
3,390 |
Total soy intake:
High vs. Low
|
0.80 (0.64-0.99) |
| |
|
|
Tofu intake:
<=3 times/month vs.
>=3 times/week
|
0.89 (0.72-1.12) |
Wu et al. [12]
|
597
|
966
|
Tofu intake:
≥120 times/year vs.
<13 times/year
|
0.7
(0.4-1.0)
|
Wu et al. [13]
|
501
|
594
|
Soy intake during adulthood:
High vs. Low
|
0.61
(0.39-0.97)
|
Shannon et al. [14]
|
378
|
1,070
|
Soy products:
>=1 servings/day vs.
<=2.6 servings/week
|
1.07
(0.68-1.69)
|
| Kim et al. [15] |
362 |
362 |
Total soyfood intake:
High vs. Low
|
0.46 (0.26-0.83) |
| |
|
|
Tofu intake:
High vs. Low
|
0.31 (0.17-0.57) |
Do et al. [16]
|
359
|
708
|
Total soyfood intake:
High vs. Low
|
0.69
(0.48-1.52)†
|
Pooled and meta-analyses
|
Trock et al. [17]
|
981,379
|
Multiple measures of soy intake:
High vs. Low
|
0.86
(0.75-0.99)§
|
| |
|
Per one gram increase of soy protein intake
|
0.97
(0.94-1.00)¶
|
Wu et al. [18]
|
8 studies
(Asian and Asian American women only)
|
Total soyfood intake:
>=20 mg/day vs.
<=5 mg/day
|
0.71 (0.60-0.85) |
| |
|
Total soyfood intake:
10-20 mg/day vs.
<=5 mg/day
|
0.88 (0.78-0.98) |
| |
11 studies
(Western women only)
|
Total soyfood intake:
>=0.8 mg/day vs.
<=0.2 mg/day
|
1.04 (0.97-1.11) |
Qin et al. [19]
|
21 studies
|
Total soyfood intake:
High vs. Low
|
0.75
(0.59-0.95)
|
| |
|
Total tofu intake:
High vs. Low
|
0.78
(0.69-0.88)
|
| |
|
Total miso intake:
High vs. Low
|
0.88
(0.78-1.00)
|
* When postmenopausal women studied separately, similar non-statistically significant results were found.
† Relative risks for postmenopausal women. Relative risk among premenopausal women was also not statistically significant, 0.76 (0.45-1.67).
‡ All women in study were premenopausal.
§ Relative risks are for all women. For premenopausal women relative risk was 0.70 (0.58-0.85), and for postmenopausal women, relative risk was 0.77 (0.60-0.98). Authors caution interpreting a protective effect due to potential problems with measures of soy intake and lack of a dose-response relationship between soy and breast cancer risk. a dose-response relationship between soy and breast cancer risk.
References
1. Wu AH, Koh WP, Wang R, Lee HP, Yu MC. Soy intake and breast cancer risk in Singapore Chinese Health Study. Br J Cancer. 99(1):196-200, 2008.
2. Lee SA, Shu XO, Li H, et al. Adolescent and adult soy food intake and breast cancer risk: results from the Shanghai Women's Health Study. Am J Clin Nutr. 89(6):1920-6, 2009.
3. Travis RC, Allen NE, Appleby PN, Spencer EA, Roddam AW, Key TJ. A prospective study of vegetarianism and isoflavone intake in relation to breast cancer risk in British women. Int J Cancer.122(3):705-10, 2008.
4. Key TJ, Appleby PN, Beral V, et al. Soya foods and breast cancer risk: a prospective study in Hiroshima and Nagasaki, Japan. Br J Cancer. 81(7):1248-1256, 1999.
5. Yamamoto S, Sobue T, Kobayashi M, Sasaki S, Tsugane S; Japan Public Health Center-Based Prospective Study on Cancer Cardiovascular Diseases Group. Soy, isoflavones, and breast cancer risk in Japan. J Natl Cancer Inst. 95(12):906-13, 2003.
6. Nishio K, Niwa Y, Toyoshima H, et al. Consumption of soy foods and the risk of breast cancer: findings from the Japan Collaborative Cohort (JACC) Study. Cancer Causes Control. 18(8):801-8, 2007.
7. Sanderson M, Shu XO, Yu H, et al. Insulin-like growth factor-I, soy protein intake, and breast cancer risk. Nutr Cancer. 50(1):8-15, 2004.
8. Horn-Ross PL, John EM, Lee M, et al. Phytoestrogen consumption and breast cancer risk in a multiethnic population: the Bay Area Breast Cancer Study. Am J Epidemiol. 154(5):434-41, 2001.
9. Hirose K, Tajima K, Hamajima N, et al. A large-scale, hospital-based case-control study of risk factors of breast cancer according to menopausal status. Jpn J Cancer Res. 86(2):146-54, 1995.
10. Yuan JM, Wang QS, Ross RK, et al. Diet and breast cancer in Shanghai and Tianjin, China. Br J Cancer. 71(6):1353-8, 1995.
11. Suzuki T, Matsuo K, Tsunoda N, et al. Effect of soybean on breast cancer according to receptor status: a case-control study in Japan. Int J Cancer. 123(7):1674-80, 2008.
12. Wu, AH, Ziegler RG, Horn-Ross PL, et al. Tofu and risk of breast cancer in Asian-Americans. Cancer Epidemiol Biomarkers Prev. 5(11):901-6, 1996.
13. Wu AH, Wan P, Hankin J, Tseng CC, Yu MC, Pike MC. Adolescent and adult soy intake and risk of breast cancer in Asian-Americans. Carcinogenesis. 23(9):1491-6, 2002.
14. Shannon J, Ray R, Wu C, et al. Food and botanical groupings and risk of breast cancer: a case-control study in Shanghai, China. Cancer Epidemiol Biomarkers Prev. 14(1):81-90, 2005.
15. Kim MK, Kim JH, Nam SJ, Ryu S, Kong G. Dietary intake of soy protein and tofu in association with breast cancer risk based on a case-control study. Nutr Cancer. 60(5):568-76, 2008.
16. Do MH, Lee SS, Kim JY, Jung PJ, Lee MH. Fruits, vegetables, soy foods and breast cancer in pre- and postmenopausal Korean women: a case-control study. Int J Vitam Nutr Res. 77(2):130-41, 2007.
17. Trock BJ, Hilakivi-Clarke L, Clarke R. Meta-analysis of soy intake and breast cancer risk. J Natl Cancer Inst. 98(7):459-71, 2006.
18. Wu AH, Yu MC, Tseng CC, Pike MC. Epidemiology of soy exposures and breast cancer risk. Br J Cancer. 98(1):9-14, 2008.
19. Qin LQ, Xu JY, Wany PY, Hoshi K. Soyfood intake in the prevention of breast cancer risk in women: a meta-analysis of observational epidemiological studies. J Nutr Sci Vitaminol (Tokyo). 52(6):428-36, 2006.
Updated 09/17/09
