Table 1. The characteristics of the included prospective cohort studies.
| Studies | Country | Period | Ethnicity | Duration (years) | Population# | Number of all cases | Age (years) | NOS score | Menstrual status | Exposure | Adjustment for Covariates | |
| Time | Place | |||||||||||
| 1999, Jee | Korea | 1994–1997 | Asian | 3.5 | 160,130 | 138 | 40–88 | 8 | NA | NA | Home | Age, husband's age, husband's occupation, husband's vegetable consumption, residency, socioeconomic status |
| 2001,Nishino | Japan | 1984–1992 | Asian | 9.0 | 9,675 | 67 | >40 y | 7 | NA | NA | Home | Age |
| 2005, Gram | Norway, Sweden | 1991–1992 | Caucasian | 9.3 | 102,098 | 1130 | 30–50 | 7 | NA | NA | Home | Age, age at menarche, age at first birth, alcohol, BMI, family history of breast cancer, hormonal contraceptive use, menopausal status, number of children |
| 2005,Hanaoka | Japan | 1990–1999 | Asian | 10.0 | 20,191 | 162 | 40–59 y | 8 | Premenopausal or postmenopausal | NA | NA | Age, employment status, education level, BMI, family history of breast cancer, history of past benign breast disease, age at menarche, number of births, menopausal status, hormone use and alcohol consumption. |
| 2008,Lin | Japan | 1988–1990 | Asian | 12.0 | 32,023 | 196 | 40–79 y | 8 | NA | Childhood or adulthood | Home or public place | Age, area, BMI, family history of breast cancer, alcohol, daily walking, age at menarche, age at the first birth, menopausal status, number of births and use of sex hormones. |
| 2008,Pirie | UK | 1996–2001 | Caucasian | 3.5 | 224,917 | 2,344 | 50–64 y | 7 | Premenopausal or postmenopausal | Childhood or adulthood | NA | Age, BMI, age at first birth, age at menarche, region of residence, socio-economic group, physical activity, alcohol consumption, menopausal status, parity, hormone use. |
| 2009,Reynolds | US | 1997 | Caucasian | 10.0 | 57,523 | 1,754 | NA | 6 | Premenopausal or postmenopausal | Childhood or adulthood | Home or workplace | Age, race, family history of breast cancer, age at menarche, pregnancy history, lifetime duration of breastfeeding, physical activity, alcohol consumption, BMI, menopausal status with use of hormone therapy. |
| 2011,Chuang | Multi-countries* | 1992–1998 | Caucasian | 10.0 | 98,938 | 3,411 | 25–70 y | 8 | NA | Childhood | NA | Age, sex, and study center, and adjusted for education, baseline alcohol drinking, BMI, physical activity, vegetable intake, fruit intake, non-alcoholic energy intake, and adulthood passive smoking, age at menarche, parity, ever use of oral contraceptives, and menopausal status |
| 2011,Luo | US | 1993–1998 | Caucasian | 10.3 | 41,022 | 3,520 | 50–79 y | 8 | Postmenopausal | Childhood or adulthood | Home or workplace | Age, race, parity, education, BMI, physical activity, alcohol intake, family history of breast cancer, hormone use |
| 2011,Xue | US | 1982–2006 | Caucasian | 24.0 | 36,017 | 2,109 | 30–55 y | 7 | NA | NA | Home or workplace | Age, family history of breast cancer, history of benign breast disease, BMI, BMI at age 18 years, height, alcohol consumption, age at menarche, parity, age at first birth, physical activity, oral contraceptive use, menopausal status, hormone use, and age at menopause. |
BMI: Body mass index; CI: Confidence interval; NA: Not available; NOS: Newcastle-Ottawa-Scale; RR: Relative risk; US: United States.
*
Multi-countries contain Sweden, Denmark, Norway, the Netherlands, UK, France, Germany, Spain, Italy, and Greece.
#
Number of non-smoking women.