Table 2.
Hazard ratios and 95% confidence intervals for the risk of colorectal cancer associated with iron intakes, EPIC cohort study, 1992–2014.
| Quintiles of intakea | Ptrend | Continuous, per SD incrementb,c | |||||
|---|---|---|---|---|---|---|---|
| Quintile 1 | Quintile 2 | Quintile 3 | Quintile 4 | Quintile 5 | |||
| Men | |||||||
| Total iron | |||||||
| Median intake (IQR), mg/day | 9.3 (8.1; 10.2) | 12.0 (11.5; 12.6) | 14.1 (13.6; 14.6) | 16.4 (15.8; 17.2) | 20.5 (19.1; 23.0) | Per 4.7 mg | |
| n cases | 551 | 563 | 495 | 537 | 505 | 2651 | |
| Model 1 | 1.00 (Ref.) | 0.96 (0.85, 1.08) | 0.88 (0.78, 0.99) | 0.95 (0.85, 1.07) | 0.85 (0.75, 0.96) | 0.017 | 0.96 (0.92, 1.00) |
| Model 2 | 1.00 (Ref.) | 0.96 (0.85, 1.09) | 0.87 (0.77, 1.00) | 0.95 (0.82, 1.10) | 0.82 (0.69, 0.98) | 0.066 | 0.96 (0.90, 1.02) |
| Model 3 | 1.00 (Ref.) | 0.98 (0.87, 1.11) | 0.90 (0.79, 1.03) | 0.99 (0.86, 1.15) | 0.88 (0.73, 1.06) | 0.317 | 0.96 (0.90, 1.02) |
| Heme iron | |||||||
| Median intake (IQR), mg/day | 0.51 (0.2; 0.7) | 1.2 (1.0; 1.3) | 1.7 (1.6; 1.8) | 2.2 (2.1; 2.4) | 3.2 (2.9; 3.9) | Per 1.2 mg | |
| n cases | 435 | 488 | 575 | 582 | 571 | 2651 | |
| Model 1 | 1.00 (Ref.) | 1.09 (0.96, 1.23) | 1.12 (0.99, 1.26) | 1.09 (0.96, 1.24) | 1.16 (1.02, 1.31) | 0.040 | 1.05 (1.01, 1.09) |
| Model 2 | 1.00 (Ref.) | 1.07 (0.95, 1.22) | 1.10 (0.97, 1.25) | 1.07 (0.94, 1.22) | 1.13 (0.99, 1.29) | 0.135 | 1.04 (1.00, 1.09) |
| Model 3 | 1.00 (Ref.) | 1.07 (0.94, 1.21) | 1.09 (0.96, 1.23) | 1.05 (0.92, 1.20) | 1.10 (0.96, 1.27) | 0.270 | 1.03 (0.99, 1.08) |
| Non-heme iron | |||||||
| Median intake (IQR), mg/day | 8.1 (7.0; 8.8) | 10.5 (10.0; 11.0) | 12.4 (11.9; 12.8) | 14.4 (13.9; 15.1) | 18.1 (16.8; 20.2) | Per 4.1 mg | |
| n cases | 583 | 561 | 503 | 518 | 486 | 2651 | |
| Model 1 | 1.00 (Ref.) | 0.93 (0.82, 1.04) | 0.87 (0.78, 0.98) | 0.87 (0.78, 0.98) | 0.82 (0.72, 0.92) | 0.001 | 0.94 (0.91, 0.98) |
| Model 2 | 1.00 (Ref.) | 0.92 (0.82, 1.04) | 0.86 (0.76, 0.99) | 0.86 (0.74, 0.99) | 0.78 (0.65, 0.92) | 0.005 | 0.93 (0.88, 0.99) |
| Model 3 | 1.00 (Ref.) | 0.93 (0.82, 1.05) | 0.88 (0.77, 1.00) | 0.88 (0.76, 1.01) | 0.80 (0.67, 0.96) | 0.019 | 0.94 (0.89, 1.00) |
| Women | |||||||
| Total iron | |||||||
| Median intake (IQR), mg/day | 7.8 (6.9; 8.5) | 10.1 (9.6; 10.5) | 11.8 (11.4; 12.2) | 13.7 (13.2; 14.3) | 17.1 (15.9; 19.0) | Per 3.8 mg | |
| n cases | 758 | 726 | 762 | 704 | 561 | 3511 | |
| Model 1 | 1.00 (Ref.) | 1.00 (0.90, 1.11) | 1.03 (0.93, 1.14) | 1.10 (0.99, 1.22) | 0.95 (0.85, 1.06) | 0.919 | 0.99 (0.96, 1.03) |
| Model 2 | 1.00 (Ref.) | 1.02 (0.92, 1.14) | 1.07 (0.96, 1.20) | 1.17 (1.03, 1.32) | 1.03 (0.89, 1.20) | 0.156 | 1.02 (0.97, 1.07) |
| Model 3 | 1.00 (Ref.) | 1.04 (0.93, 1.16) | 1.11 (0.98, 1.25) | 1.22 (1.07, 1.40) | 1.11 (0.94, 1.31) | 0.025 | 1.02 (0.97, 1.07) |
| Heme iron | |||||||
| Median intake (IQR), mg/day | 0.3 (0.1; 0.4) | 0.75 (0.7; 0.8) | 1.1 (1.0; 1.2) | 1.5 (1.4; 1.6) | 2.2 (2.0; 2.7) | Per 0.8 mg | |
| n cases | 608 | 719 | 789 | 771 | 624 | 3511 | |
| Model 1 | 1.00 (Ref.) | 1.03 (0.92, 1.14) | 1.02 (0.92, 1.14) | 1.07 (0.97, 1.19) | 1.02 (0.92, 1.14) | 0.457 | 1.01 (0.97, 1.04) |
| Model 2 | 1.00 (Ref.) | 1.02 (0.92, 1.14) | 1.01 (0.90, 1.12) | 1.06 (0.95, 1.18) | 1.00 (0.89, 1.12) | 0.743 | 1.00 (0.96, 1.04) |
| Model 3 | 1.00 (Ref.) | 1.00 (0.90, 1.12) | 0.98 (0.88, 1.09) | 1.01 (0.91, 1.13) | 0.95 (0.84, 1.07) | 0.504 | 0.98 (0.95, 1.02) |
| Non heme iron | |||||||
| Median intake (IQR), mg/day | 7.0 (6.1; 7.6) | 9.0 (8.6; 9.4) | 10.6 (10.2; 11.0) | 12.4 (11.9; 12.9) | 15.4 (14.4; 17.1) | Per 3.4 mg | |
| n cases | 775 | 757 | 706 | 713 | 560 | 3511 | |
| Model 1 | 1.00 (Ref.) | 0.98 (0.89, 1.09) | 1.04 (0.94, 1.15) | 1.06 (0.96, 1.18) | 0.93 (0.84, 1.04) | 0.710 | 0.99 (0.96, 1.02) |
| Model 2 | 1.00 (Ref.) | 1.01 (0.90, 1.12) | 1.08 (0.96, 1.21) | 1.12 (0.99, 1.27) | 1.00 (0.86, 1.17) | 0.344 | 1.02 (0.97, 1.07) |
| Model 3 | 1.00 (Ref.) | 1.01 (0.91, 1.13) | 1.09 (0.97, 1.23) | 1.14 (1.01, 1.30) | 1.03 (0.88, 1.20) | 0.209 | 1.03 (0.98, 1.09) |
IQR interquartile range.
aThe analyses were run using country-specific quintiles.
bFor the continuous analysis, all the models were adjusted for the same variables as the in quintiles analysis, but with additional stratification by country.
cP values for heterogeneity by sex (using continuous values) for total iron, heme iron, and non-heme iron, respectively, were for Model 1, 0.124, 0.260 and 0.031; and Model 2, 0.528, 0.091, and 0.176; and Model 3, 0.802, 0.081, 0.308.
Model 1 was stratified by age at recruitment.
Model 2 was model 1 additionally adjusted for BMI, height, education, physical activity, smoking, energy intakes from alcohol, and total energy minus energy from alcohol.
Model 3 was model 2 additionally adjusted for intakes of vitamin C, calcium, tea, coffee, and in women specifically menopause status and hormone use. Model 3 for heme iron additionally included intakes of cereal, and cereal products, legumes, and vegetables whereas model 3 for non-heme iron included intakes of red meat, processed meats, poultry, and fish and fish products.