Background
Methods
Selection of studies
Data extraction and classification
Quality assessment
Statistical analysis
Results
Authors and publication year | Study design | Country | Study period | Cases/subjects | Exposure range | RR (95 % CI) | Variables of adjustment | Study qualitya
| Other variables evaluated | Assessment |
---|---|---|---|---|---|---|---|---|---|---|
Oishi et al. 1988 [26] | HCC | Japan | 1981–1984 | 100/200 | Ever vs. none | 0.78 (0.45–1.37) | Age | 5 | None | Interview FFQ (31 items) |
Walker et al. 1992 [27] | PCC | South Africa | 1998–1990 | 166/332 | ≥15 vs. <15 g/day | 0.6 (0.4–1.0) | Age | 6 | None | Interview FFQ (unknown items) |
Andersson et al. [35] | PCC | Sweden | 1989–1994 | 526/1062 | The highest quartile (≥25.9 g/day) vs. the lowest (<15.9 g/day) | 0.82 (0.58–1.15) | Age, energy | 6 | Advanced prostate cancer | Interview and self-administered questionnaire FFQ (68 items) |
Vlajinac et al. 1997 [28] | HCC | Serbia | 1990–1994 | 101/303 | The highest tertile vs. the lowest | 4.02 (1.38–11.73) | Age, residence, energy, protein, fat total, saturated fatty acids, carbohydrate, total sugar, retinol, retinol equivalent, a-tocopherol, folic acid, vitamin B12, sodium, potassium, calcium, phosphorus, magnesium, and iron | 6 | None | Interview FFQ (150 items) |
Deneo-Pellegrini et al. 1999 [29] | HCC | Uruguay | 1993–1997 | 175/408 | The highest quartile (≥27.2 g/day) vs. the lowest (<18.2 g/day) | 1.5 (0.8–2.6) | Age, residence, urban/rural status, education, family history of prostate cancer, BMI, and total energy intake | 6 | None | Interview FFQ (64 items) |
Ramon et al. 2000 [30] | HCC | Spain | 1994–1998 | 270/704 | The highest quartile (≥39.5 g/day) vs. the lowest (<13.1 g/day) | 1.0 (0.7–1.5) | Age, residence, family history of prostate cancer, BMI, and energy intake | 8 | None | Interview FFQ (141 items) |
Lu et al. 2001 [31] | PCC | USA | 1993–1997 | 65/197 | The highest quartile (≥13.7 g/day) vs. the lowest (<7.9 g/day) | 1.81 (0.55–5.96) | Age, race, education, alcohol drinking, pack-years of smoking, family history of prostate cancer, and total dietary caloric intake | 8 | None | Interview FFQ (98 items) |
Pelucchi et al. 2004 [32] | HCC | Italy | 1991–2002 | 1294/1745 | The highest quintile (≥21.1 g/day) vs. the lowest (<12.3 g/day) | 0.93 (0.71–1.22) | Age, study center, education, family history of prostate cancer, smoking habit, alcohol consumption and total energy intake | 7 | Insoluble fiber, cellulose, vegetable fiber, fruit fiber, grain fiber. | Interview FFQ (78 items) |
McCann et al. 2005 [33] | PCC | USA | 1986–1991 | 433/971 | The highest quartile (>38 g/day) vs. the lowest ≤15 g/day | 1.21 (0.73–2.01) | Age, education, BMI, cigarette smoking status, and total energy | 7 | None | Interview FFQ (172 items) |
Walker et al. 2005 [34] | HCC | Canada | 1997–1999 | 80/414 | The highest tertile vs. the lowest | 1.10 (0.58–2.07) | Age, alcohol, energy, fat, carbohydrate, calcium, protein, and cholesterol intake | 6 | None | Interview FFQ (66 items) |
Lewis et al. 2009 [36] | HCC | USA | 1998–2004 | 478/860 | The highest tertile (≥20.7 g/day) vs. the lowest (<13.7 g/day) | 0.56 (0.35–0.89) | Age, education, BMI, smoking history, family history of prostate cancer in first-degree relatives, and total caloric intake | 6 | None | Self-administered questionnaire FFQ (100 items) |
Suzuki et al. 2009 [9] | Cohort | Europe | 1993–2007 | 2747/142,590 | The highest quintile (≥30.4 g/day) vs. the lowest (<17.8 g/day) | 1.02 (0.87–1.19) | Age, energy intake, height, weight, smoking, education, and marital status | 8 | Vegetables fiber, fruit fiber, cereal fiber Local, advanced, low-grade, and high-grade prostate cancer | |
Nimptsch et al. 2011 [10] | Cohort | USA | 1986–2002 | 5112/49,934 | The highest quintile (≥26 g/day) vs. the lowest (≤15.4 g/day) | 1.01 (0.92–1.12) | Age, BMI, height, history of diabetes, family history of prostate cancer, race, smoking, vigorous physical activity, energy intake, alcohol intake, calcium intake, alphalinolenic acid, and tomato sauce | 7 | Local, advanced, low-grade and high-grade prostate cancer | Self-administered questionnaire FFQ (131 items) |
Drake et al. 2012 [11] | Cohort | Sweden | 1991–2009 | 817/8128 | The highest quintile (≥23.7 g/day) vs. (17.6 g/day) the lowest | 1.15 (0.89–1.49) | Age, year of study entry, season of data collection, energy intake, height, waist, physical activity, smoking, educational level, birth in Sweden, alcohol, calcium, selenium | 9 | Low-risk, high-risk, and symptomatic prostate cancer | Interview FFQ (168 items) |
Deschasaux et al. 2014 [12] | Cohort | France | 1994–2007 | 139/3313 | The highest quartile vs. the lowest | 0.47 (0.27–0.81) | Age, energy intake without alcohol, intervention group, number of 24-h dietary records, smoking status, educational level, physical activity, height, BMI, alcohol intake, family history of prostate cancer, prostate-specific antigen, calcium intake, processed meat intake, tomato product intake, vitamin E intake, and blood selenium | 7 | Soluble fiber, insoluble fiber, cereal fiber, vegetable fiber, fruit fiber, legume fiber | 24-h dietary record |
Vidal et al. 2015 [37] | HCC | USA | 2007–2012 | 156/430 | The highest tertile vs. the lowest | 0.79 (0.31–1.97) | Age, race, family history, caloric intake, carbohydrate intake, BMI, diabetes, physical activity, alcohol, and smoking status | 6 | Low-grade and high-grade prostate cancer | Interview FFQ (61 items) |
Sawada et al. 2015 [13] | Cohort | Japan | 1995–2009 | 825/43,435 | The highest quartile vs. the lowest | 1.00 (0.77, 1.29) | Age, public health center area, smoking status, drinking frequency, marital status, BMI, and intakes of green tea, genistein, SFAs, and carbohydrate | 7 | Soluble fiber, insoluble fiber, local and advanced prostate cancer | Self-administered questionnaire FFQ (138 items) |
Outcome of interest | No. of studies | OR (95 % CI) |
p
heterogenity
|
I
2 (%) |
p for interaction |
---|---|---|---|---|---|
Total dietary fiber | 17 | 0.89 (0.77, 1.01) | 0.005 | 53.6 | |
Study design | |||||
Cohort | 5 | 0.94 (0.77, 1.11) | 0.004 | 74.3 | 0.202 |
Case-control | 12 | 0.82 (0.68, 0.96) | 0.277 | 17.0 | |
Study quality | |||||
Low | 8 | 0.73 (0.56, 0.90) | 0.335 | 12.2 | 0.033 |
High | 9 | 0.96 (0.83, 1.08) | 0.04 | 51.7 | |
Geographical region | |||||
Europe | 7 | 0.90 (0.71, 1.09) | 0.01 | 63.5 | 0.937 |
North America | 6 | 0.90 (0.64, 1.16) | 0.059 | 53.1 | |
Japan | 2 | 0.95 (0.72, 1.17) | 0.41 | 0 | |
Assessment | |||||
Interview | 11 | 0.94 (0.79, 1.10) | 0.313 | 13.8 | 0.931 |
Questionnaire | 4 | 0.93 (0.76, 1.09) | 0.02 | 69.7 | |
Family history | |||||
Yes | 8 | 0.84 (0.62, 1.05) | 0.002 | 69.4 | 0.44 |
No | 9 | 0.94 (0.81, 1.08) | 0.187 | 29.0 | |
BMI | |||||
Yes | 8 | 0.87 (0.66, 1.08) | 0.001 | 70.3 | 0.695 |
No | 9 | 0.92 (0.79, 1.06) | 0.21 | 26.4 | |
Energy intake | |||||
Yes | 14 | 0.91 (0.78, 1.04) | 0.007 | 55.1 | 0.507 |
No | 3 | 0.81 (0.54, 1.07) | 0.14 | 49.2 | |
Multiple confoundersa
| |||||
Yes | 6 | 0.82 (0.54, 1.09) | 0.306 | 14.4 | 0.387 |
No | 11 | 0.95 (0.84, 1.05) | <0.001 | 77.7 | |
Tumor stage | |||||
Local | 3 | 0.98 (0.89, 1.08) | 0.24 | 30.5 | 0.562 |
Advanced | 4 | 0.93 (0.79, 1.07) | 0.24 | 29.3 | |
Source of intake | |||||
Cereal fiber | 3 | 1.05 (0.94, 1.16) | 0.52 | 0 | 0.02 |
Fruit fiber | 3 | 0.92 (0.81, 1.03) | 0.55 | 0 | |
Vegetable fiber | 3 | 0.87 (0.53, 1.21) | 0.001 | 84.8 | |
Legume fiber | 1 | 0.55 (0.32, 0.95) | NA | NA | |
Solubility | |||||
Soluble fiber | 2 | 0.87 (0.52, 1.22) | 0.13 | 57.2 | 0.777 |
Insoluble fiber | 3 | 0.80 (0.46, 1.13) | 0.005 | 81.0 |