Introduction
Materials and methods
Study population
Data collection
Assessment of PCa
Statistical analysis
Results
Characteristics of the study participants
Characteristics | Controls | Cases | P* | |||
---|---|---|---|---|---|---|
No. of controls | % | No. of cases | % | |||
Total | 47,922 | 88.20 | 6,414 | 11.80 | ||
Age | 3.47E-55 | |||||
≤ 59 years | 16,125 | 33.65 | 1,534 | 23.92 | ||
60–64 years | 15,005 | 31.31 | 2,210 | 34.46 | ||
65–69 years | 10,907 | 22.76 | 1,789 | 27.89 | ||
≥ 70 years | 5,885 | 12.28 | 881 | 13.74 | ||
BMI (kg/m2) | 5.18E-08 | |||||
≤ 18.5 | 131 | 0.27 | 12 | 0.19 | ||
> 18.5 and ≤ 25 | 11,649 | 24.31 | 1,690 | 26.35 | ||
> 25 and ≤ 30 | 23,713 | 49.48 | 3,260 | 50.83 | ||
> 30 | 10,817 | 22.57 | 1,242 | 19.36 | ||
Missing | 1,612 | 3.36 | 210 | 3.27 | ||
Education | 0.033 | |||||
≤High school | 17,925 | 37.40 | 2,319 | 36.16 | ||
≥Some college | 28,945 | 60.40 | 3,973 | 61.94 | ||
Missing | 1,052 | 2.20 | 122 | 1.90 | ||
Race | 2.66E-16 | |||||
White, Non-Hispanic | 42,676 | 89.05 | 5,781 | 90.13 | ||
Black, Non-Hispanic | 1,213 | 2.53 | 247 | 3.85 | ||
Hispanic | 817 | 1.70 | 92 | 1.43 | ||
Asian | 1,897 | 3.96 | 150 | 2.34 | ||
Pacific Islander | 250 | 0.52 | 23 | 0.36 | ||
American Indian | 99 | 0.21 | 10 | 0.16 | ||
Missing | 970 | 2.02 | 111 | 1.73 | ||
Pack-year smoking | 1.44E-13 | |||||
Never | 17,334 | 36.17 | 2,619 | 40.83 | ||
≤ 20 | 9,485 | 19.79 | 1,273 | 19.85 | ||
> 20 | 19,498 | 40.69 | 2,340 | 36.48 | ||
Missing | 1,605 | 3.35 | 182 | 2.84 | ||
Drinking intensity | 0.255 | |||||
Never | 11,284 | 23.55 | 1,496 | 23.32 | ||
≤ 5 | 15,617 | 32.59 | 2,026 | 31.59 | ||
> 5 and ≤ 10 | 5,468 | 11.41 | 777 | 12.11 | ||
> 10 and ≤ 20 | 5,466 | 11.41 | 732 | 11.41 | ||
> 20 and ≤ 30 | 4,425 | 9.23 | 631 | 9.84 | ||
> 30 | 5,662 | 11.82 | 752 | 11.72 | ||
Marital status | 2.23E-07 | |||||
Married | 39,881 | 83.22 | 5,524 | 86.12 | ||
Widowed | 1,522 | 3.18 | 192 | 2.99 | ||
Divorced | 3,602 | 7.52 | 379 | 5.91 | ||
Separated | 396 | 0.83 | 47 | 0.73 | ||
Never married | 1,469 | 3.07 | 150 | 2.34 | ||
Missing | 1,052 | 2.20 | 122 | 1.90 | ||
Family history | 2.93E-31 | |||||
No | 42,567 | 88.83 | 5,471 | 85.30 | ||
Yes | 3,267 | 6.82 | 702 | 10.94 | ||
Possibly-relative | 720 | 1.50 | 89 | 1.39 | ||
Missing | 1,368 | 2.85 | 152 | 2.37 | ||
Total energy intake (kcal/day) | 0.062† | |||||
Mean ± SD | 1,996 ± 814 | 1,975 ± 806 | ||||
Total vegetable intake (g/day) | 0.929† | |||||
Mean ± SD | 290 ± 194 | 291 ± 189 | ||||
Total fruit intake (g/day) | 0.012† | |||||
Mean ± SD | 265 ± 223 | 273 ± 222 | ||||
Total calcium intake (mg/day) | 0.169† | |||||
Mean ± SD | 922 ± 501 | 931 ± 498 | ||||
Total folate intake (mcg/day) | 0.311† | |||||
Mean ± SD | 609 ± 277 | 613 ± 277 |
Associations between fiber intake and PCa risk
Nutrients | Controls | Cases | aHR* | 95% CI | P |
---|---|---|---|---|---|
Total fiber (g/day) | |||||
Q1 (0.74–12.84) | 12,006 | 1,584 | 1.00 (reference) | ||
Q2 (12.85–17.70) | 11,992 | 1,607 | 0.96 | 0.89–1.04 | 0.346 |
Q3 (17.71–23.74) | 11,934 | 1,638 | 0.97 | 0.89–1.05 | 0.420 |
Q4 (23.75–97.82) | 11,990 | 1,585 | 0.90 | 0.80–1.01 | 0.073 |
Insoluble fiber (g/day) | |||||
Q1 (0.42–8.34) | 12,028 | 1,578 | 1.00 (reference) | ||
Q2 (8.35–11.60) | 11,986 | 1,617 | 0.97 | 0.90–1.05 | 0.453 |
Q3 (11.61–15.69) | 11,890 | 1,660 | 0.97 | 0.90–1.06 | 0.526 |
Q4 (15.70–65.67) | 12,018 | 1,559 | 0.87 | 0.78–0.98 | 0.016 |
Soluble fiber (g/day) | |||||
Q1 (0.31–4.31) | 12,053 | 1,589 | 1.00 (reference) | ||
Q2 (4.32–5.90) | 11,983 | 1,615 | 0.98 | 0.91–1.06 | 0.638 |
Q3 (5.91–7.91) | 11,915 | 1,643 | 0.98 | 0.89–1.06 | 0.576 |
Q4 (7.92–36.66) | 11,971 | 1,567 | 0.90 | 0.80–1.02 | 0.086 |
Subgroup analyses for the effect of fiber intake on PCa risk
Variables | Total fiber | Insoluble fiber | Soluble fiber | |||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Age | aHR* | 95% CI | P | aHR* | 95% CI | P | aHR* | 95% CI | P | |||
Age ≤ 65 | Q1 | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | ||||||||
Q2 | 1.01 | 0.92–1.11 | 0.818 | 1.02 | 0.93–1.12 | 0.674 | 1.00 | 0.91–1.10 | 0.962 | |||
Q3 | 1.07 | 0.96–1.19 | 0.241 | 1.09 | 0.98–1.20 | 0.127 | 1.03 | 0.92–1.15 | 0.598 | |||
Q4 | 1.02 | 0.88–1.18 | 0.806 | 0.99 | 0.86–1.13 | 0.847 | 0.96 | 0.82–1.11 | 0.555 | |||
Age > 65 | Q1 | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | ||||||||
Q2 | 0.89 | 0.79–1.01 | 0.078 | 0.91 | 0.80–1.03 | 0.133 | 0.99 | 0.88–1.13 | 0.920 | |||
Q3 | 0.80 | 0.70–0.93 | 0.002 | 0.82 | 0.71–0.94 | 0.004 | 0.87 | 0.75–1.00 | 0.055 | |||
Q4 | 0.70 | 0.57–0.84 | < 0.001 | 0.72 | 0.60–0.87 | 0.001 | 0.81 | 0.66–0.99 | 0.042 | |||
BMI | ||||||||||||
BMI ≤ 25 | Q1 | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | ||||||||
Q2 | 1.05 | 0.91–1.22 | 0.500 | 1.04 | 0.90–1.20 | 0.579 | 1.06 | 0.92–1.23 | 0.408 | |||
Q3 | 1.10 | 0.94–1.29 | 0.250 | 1.09 | 0.93–1.27 | 0.313 | 1.00 | 0.85–1.18 | 0.957 | |||
Q4 | 0.88 | 0.71–1.09 | 0.226 | 0.88 | 0.72–1.09 | 0.244 | 0.89 | 0.71–1.11 | 0.291 | |||
BMI > 25 | Q1 | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | ||||||||
Q2 | 0.95 | 0.87–1.04 | 0.292 | 0.96 | 0.88–1.05 | 0.354 | 0.95 | 0.87–1.04 | 0.305 | |||
Q3 | 0.92 | 0.83–1.02 | 0.103 | 0.92 | 0.84–1.02 | 0.109 | 0.97 | 0.87–1.07 | 0.518 | |||
Q4 | 0.91 | 0.79–1.04 | 0.164 | 0.89 | 0.78–1.01 | 0.070 | 0.92 | 0.79–1.06 | 0.246 | |||
Smoking | ||||||||||||
No | Q1 | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | ||||||||
Q2 | 0.94 | 0.84–1.06 | 0.330 | 0.93 | 0.83–1.04 | 0.186 | 0.91 | 0.81–1.03 | 0.131 | |||
Q3 | 0.96 | 0.84–1.09 | 0.523 | 0.91 | 0.80–1.04 | 0.165 | 0.92 | 0.81–1.06 | 0.243 | |||
Q4 | 0.79 | 0.66–0.95 | 0.010 | 0.79 | 0.67–0.94 | 0.007 | 0.79 | 0.65–0.95 | 0.013 | |||
Yes, currently | Q1 | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | ||||||||
Q2 | 0.94 | 0.72–1.22 | 0.633 | 1.06 | 0.81–1.39 | 0.654 | 0.93 | 0.72–1.21 | 0.605 | |||
Q3 | 1.08 | 0.81–1.45 | 0.589 | 1.17 | 0.88–1.57 | 0.290 | 0.94 | 0.70–1.27 | 0.694 | |||
Q4 | 1.20 | 0.82–1.76 | 0.359 | 1.49 | 1.03–2.16 | 0.033 | 1.22 | 0.82–1.82 | 0.316 | |||
Yes, former | Q1 | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | ||||||||
Q2 | 1.00 | 0.90–1.12 | 0.956 | 0.99 | 0.89–1.10 | 0.794 | 1.01 | 0.91–1.12 | 0.865 | |||
Q3 | 0.96 | 0.85–1.08 | 0.512 | 0.96 | 0.85–1.08 | 0.507 | 1.00 | 0.88–1.13 | 0.976 | |||
Q4 | 0.93 | 0.79–1.09 | 0.378 | 0.85 | 0.72–0.99 | 0.038 | 0.96 | 0.80–1.14 | 0.603 | |||
Drinking | ||||||||||||
No | Q1 | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | ||||||||
Q2 | 0.94 | 0.71–1.23 | 0.635 | 0.93 | 0.71–1.21 | 0.582 | 0.96 | 0.72–1.26 | 0.742 | |||
Q3 | 0.85 | 0.62–1.16 | 0.307 | 0.76 | 0.56–1.04 | 0.083 | 0.89 | 0.65–1.23 | 0.484 | |||
Q4 | 0.75 | 0.48–1.16 | 0.191 | 0.70 | 0.46–1.07 | 0.098 | 0.64 | 0.40–1.01 | 0.057 | |||
Yes, currently | Q1 | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | ||||||||
Q2 | 0.96 | 0.88–1.05 | 0.338 | 0.97 | 0.89–1.05 | 0.427 | 0.97 | 0.89–1.06 | 0.500 | |||
Q3 | 0.99 | 0.90–1.09 | 0.836 | 0.99 | 0.90–1.09 | 0.817 | 0.97 | 0.88–1.07 | 0.537 | |||
Q4 | 0.94 | 0.82–1.07 | 0.328 | 0.91 | 0.80–1.03 | 0.138 | 0.96 | 0.84–1.10 | 0.561 | |||
Yes, former | Q1 | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | ||||||||
Q2 | 1.05 | 0.86–1.27 | 0.662 | 1.10 | 0.90–1.34 | 0.369 | 1.09 | 0.90–1.34 | 0.378 | |||
Q3 | 0.96 | 0.77–1.20 | 0.732 | 1.05 | 0.84–1.31 | 0.647 | 1.05 | 0.83–1.32 | 0.700 | |||
Q4 | 0.78 | 0.57–1.06 | 0.113 | 0.84 | 0.63–1.13 | 0.258 | 0.80 | 0.58–1.11 | 0.179 | |||
Education | ||||||||||||
≤high school | Q1 | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | ||||||||
Q2 | 0.92 | 0.81–1.04 | 0.175 | 0.91 | 0.81–1.03 | 0.151 | 0.99 | 0.88–1.12 | 0.900 | |||
Q3 | 0.94 | 0.82–1.08 | 0.361 | 0.98 | 0.85–1.12 | 0.710 | 0.93 | 0.80–1.07 | 0.308 | |||
Q4 | 0.79 | 0.66–0.96 | 0.018 | 0.83 | 0.69–1.00 | 0.047 | 0.88 | 0.72–1.08 | 0.229 | |||
≥some college | Q1 | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | ||||||||
Q2 | 1.00 | 0.91–1.11 | 0.933 | 0.99 | 0.90–1.08 | 0.778 | 1.00 | 0.91–1.11 | 0.938 | |||
Q3 | 1.01 | 0.90–1.12 | 0.908 | 0.97 | 0.88–1.08 | 0.631 | 1.01 | 0.90–1.12 | 0.925 | |||
Q4 | 0.96 | 0.83–1.11 | 0.572 | 0.90 | 0.78–1.03 | 0.124 | 0.92 | 0.79–1.08 | 0.304 | |||
Race | ||||||||||||
White, non–hispanic | Q1 | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | ||||||||
Q2 | 0.98 | 0.91–1.06 | 0.668 | 0.96 | 0.89–1.04 | 0.303 | 0.97 | 0.90–1.05 | 0.469 | |||
Q3 | 0.97 | 0.89–1.06 | 0.523 | 0.96 | 0.88–1.05 | 0.364 | 0.96 | 0.88–1.05 | 0.355 | |||
Q4 | 0.91 | 0.81–1.03 | 0.137 | 0.86 | 0.77–0.96 | 0.010 | 0.88 | 0.77–1.00 | 0.042 | |||
Other | Q1 | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | ||||||||
Q2 | 1.09 | 0.84–1.43 | 0.521 | 1.09 | 0.83–1.43 | 0.528 | 1.08 | 0.82–1.40 | 0.594 | |||
Q3 | 1.19 | 0.89–1.59 | 0.247 | 1.27 | 0.95–1.69 | 0.104 | 1.11 | 0.83–1.49 | 0.475 | |||
Q4 | 1.00 | 0.67–1.50 | 0.993 | 0.98 | 0.66–1.46 | 0.930 | 1.06 | 0.70–1.60 | 0.772 | |||
Family history | ||||||||||||
Yes | Q1 | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | ||||||||
Q2 | 0.86 | 0.69–1.08 | 0.203 | 0.91 | 0.73–1.15 | 0.437 | 0.91 | 0.72–1.15 | 0.434 | |||
Q3 | 0.99 | 0.77–1.28 | 0.958 | 1.05 | 0.82–1.34 | 0.716 | 1.03 | 0.79–1.33 | 0.848 | |||
Q4 | 0.91 | 0.65–1.29 | 0.603 | 0.89 | 0.64–1.24 | 0.484 | 0.94 | 0.65–1.35 | 0.735 | |||
No | Q1 | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | ||||||||
Q2 | 0.98 | 0.90–1.06 | 0.608 | 0.97 | 0.89–1.05 | 0.443 | 0.99 | 0.91–1.07 | 0.773 | |||
Q3 | 0.97 | 0.88–1.06 | 0.494 | 0.96 | 0.88–1.05 | 0.420 | 0.96 | 0.88–1.06 | 0.427 | |||
Q4 | 0.90 | 0.80–1.02 | 0.096 | 0.87 | 0.77–0.98 | 0.020 | 0.90 | 0.79–1.02 | 0.093 |
Combined outcomes of insoluble fiber intake and risk factors for PCa risk
Variables | Insoluble fiber intake* | Controls | PCa cases | aHR† | 95% CI | P |
---|---|---|---|---|---|---|
Age | ||||||
> 65 | Low | 3,663 | 591 | 1.00 (reference) | ||
> 65 | High | 3,481 | 538 | 0.81 | 0.69–0.94 | 6.41E-03 |
≤65 | Low | 8,365 | 987 | 0.73 | 0.66–0.81 | 3.98E-09 |
≤65 | High | 8,537 | 1,021 | 0.62 | 0.54–0.72 | 2.67E-10 |
Smoke status | ||||||
Current | Low | 1,767 | 177 | 1.00 (reference) | ||
Current | High | 860 | 108 | 1.07 | 0.82–1.40 | 0.599 |
No/Former | Low | 10,010 | 1,376 | 1.17 | 0.99–1.37 | 0.062 |
No/Former | High | 10,935 | 1,418 | 0.96 | 0.79–1.15 | 0.639 |
Family history | ||||||
Yes | Low | 805 | 163 | 1.00 (reference) | ||
Yes | High | 817 | 173 | 1.11 | 0.89–1.38 | 0.350 |
No | Low | 10,639 | 1,358 | 0.82 | 0.71–0.95 | 8.56E-03 |
No | High | 10,738 | 1,326 | 0.71 | 0.60–0.83 | 3.49E-05 |
Fiber intake and the prognosis of PCa patients
Nutrients | Dead | Alive | aHR* | 95% CI | P |
---|---|---|---|---|---|
Total fiber (g/day) | |||||
Q1 (1.42–12.93) | 208 | 1,399 | 1.00 (reference) | ||
Q2 (12.94–17.75) | 184 | 1,418 | 0.98 | 0.91–1.06 | 0.616 |
Q3 (17.76–23.64) | 208 | 1,394 | 1.02 | 0.93–1.11 | 0.716 |
Q4 (23.65–88.79) | 182 | 1,421 | 1.02 | 0.90–1.15 | 0.771 |
Insoluble fiber (g/day) | |||||
Q1 (0.89–8.40) | 211 | 1,399 | 1.00 (reference) | ||
Q2 (8.41–11.63) | 194 | 1,409 | 0.95 | 0.88–1.03 | 0.211 |
Q3 (11.64–15.59) | 194 | 1,408 | 0.98 | 0.90–1.06 | 0.570 |
Q4 (15.60–57.39) | 183 | 1,416 | 0.97 | 0.87–1.09 | 0.640 |
Soluble fiber (g/day) | |||||
Q1 (0.51–4.33) | 217 | 1,395 | 1.00 (reference) | ||
Q2 (4.34–5.91) | 179 | 1,422 | 0.95 | 0.88–1.02 | 0.173 |
Q3 (5.92–7.86) | 196 | 1,404 | 1.00 | 0.91–1.09 | 0.958 |
Q4 (7.87–30.71) | 190 | 1,411 | 0.95 | 0.84–1.08 | 0.438 |