Table 1. Characteristics of studies.
| References | Year | Geographic regions | Case-controls or cohort size | Age | Food frequency questionnaire (items) | Folate intake calculation method | Time frame* | Covariates | Exclusion of hysterectomy |
|---|---|---|---|---|---|---|---|---|---|
| Hospital-based case-control | |||||||||
| Tavani et al [19] | 2012 | Italy& Switzerland | 454/908 | 61.5# | 78 | IFCD | 10 years | Age.Alc.B. Edu.Engy.R.S | Not mention |
| Yeh et al [22] | 2009 | USA | 541/541 | 27-96 | 44 | USDA | 16 years | Age.B.S. Engy.H.R | Yes |
| Martinez et al [17] | 2005 | Mexico | 85/629 | 18-81 | 116 | Not mention | 2 years | Age.Alc.B. Engy.H.R | Yes |
| McCann et al [16] | 2000 | USA | 232/ 639 | 40-85 | 172 | USDA | 5 years | Age.Alc.B. Engy.H.R.S | Yes |
| Population-based case–control | |||||||||
| Biel et al [21] | 2011 | Canada | 506/ 981 | 30-79 | 124 | USDA@ | 4 years | (Age).Alc.B. Engy.H.S.R | Not mention |
| Xu et al [25] | 2007 | China | 1204/ 1212 | 30-69 | 71 | USDA& CDA | 6 years | Age.Alc.B.Edu.Engy.H.R | Yes |
| Paynter et al [18] | 2004 | USA | 201/ 603 | 30-55 | 61 | USDA | 16 years | (Age).Alc. Engy | Not mention |
| Jain et al [23] | 2000 | Canada | 552/ 562 | 40-59 | 142 | USDA | 5 years | Age.Alc.B. Engy.H.R.S | Yes |
| Potischman et al [15] | 1993 | USA | 399/ 296 | 20-74 | 60 | Not mention | 5 years | (Age).Alc.B. (Engy).H.R.S | Yes |
| Cohort Studies | |||||||||
| Liu et al ¶[13] | 2013 | USA | 788/ 121700 | 30-55 | Not mention | USDA | 26 years | Age.B.H.R.S | Yes |
| Uccella et al ¶[20] | 2011 | USA | 471/ 23356 | 55-69 | 126 | USDA | 17 years | Age.Alc.B. Engy.H.R.S | Yes |
| Uccella et al ®[20] | 2011 | USA | 71/ 23356 | 55-69 | 126 | USDA | 17 years | Age.Alc.B. Engy.H.R.S | |
| Kabat et al [24] | 2008 | Canada | 426/ 34748 | 40-59 | 86 | USDA | 16.4 years (average) | Age.Alc.B.Edu.Engy.H.R.S | Yes |
| Jain et al [14] | 2000 | Canada | 221/ 56837 | 30-79 | 86 | USDA | 10.3 years (median) | Age.B.Edu.Engy.H.R.S | Not mention |
Years of follow-up for cohort studies and duration of data collection after diagnosis for case-control studies.
Median age.
Focusing only on type I endometrial cancer.
Focusing only on type II endometrial cancer.
When estimating total folate intake, the amount of synthetic folic acid was multiplied by 1.7 in order to account for the greater bioavailability of synthetic folic acid.
Folate intake calculation method: IFCD=Italian food composition database, USDA=composition database from U.S Department of Agriculture, CDA=composition database from China Department of Agriculture
Covariates: Age=Age, Alc=Alcohol, B=BMI/weight, Edu=Education, Engy=Total Energy, H=HRT/ERT use, R=Reproductive factors, S=Smoking. (Age): matched on age. (Engy) Energy from carbohydrate calories.