Table II.
ORs and 95% CIs for the main effect of iron intake and risk of advanced colorectal adenoma and colorectal cancer
| Characteristic | Advanced colorectal adenoma | Colorectal cancer | ||||||
|---|---|---|---|---|---|---|---|---|
| Cases | Controls | ORa (95% CI) | ORb (95% CI) | Cases | Controls | ORa (95% CI) | ORb (95% CI) | |
| Total iron | ||||||||
| Quartile 1 | 361 | 331 | 1.00 | 1.00 | 107 | 117 | 1.00 | 1.00 |
| Quartile 2 | 314 | 366 | 0.77 (0.62, 0.95) | 0.86 (0.68, 1.09) | 94 | 80 | 1.31 (0.88, 1.96) | 1.36 (0.87, 2.12) |
| Quartile 3 | 272 | 335 | 0.74 (0.59, 0.92) | 0.85 (0.67, 1.08) | 84 | 112 | 0.83 (0.56, 1.21) | 0.82 (0.54, 1.25) |
| Quartile 4 | 258 | 355 | 0.66 (0.53, 0.82) | 0.86 (0.66, 1.13) | 85 | 92 | 1.03 (0.69, 1.53) | 1.13 (0.70, 1.83) |
| P-trend | 0.0001* | 0.24 | 0.82 | 0.96 | ||||
| Dietary iron | ||||||||
| Quartile 1 | 336 | 334 | 1.00 | 1.00 | 95 | 114 | 1.00 | 1.00 |
| Quartile 2 | 330 | 348 | 0.94 (0.76, 1.16) | 1.09 (0.86, 1.38) | 102 | 98 | 1.26 (0.85, 1.86) | 1.37 (0.89, 2.11) |
| Quartile 3 | 257 | 360 | 0.69 (0.56, 0.87) | 0.94 (0.71, 1.25) | 86 | 87 | 1.20 (0.80, 1.80) | 1.38 (0.83, 2.27) |
| Quartile 4 | 282 | 345 | 0.79 (0.63, 0.99) | 1.31 (0.91, 1.90) | 87 | 102 | 1.04 (0.69, 1.58) | 1.26 (0.66, 2.43) |
| P-trend | 0.01* | 0.16 | 0.99 | 0.62 | ||||
| Heme iron | ||||||||
| Quartile 1 | 266 | 352 | 1.00 | 1.00 | 87 | 95 | 1.00 | 1.00 |
| Quartile 2 | 282 | 334 | 1.13 (0.90, 1.42) | 1.07 (0.85, 1.36) | 102 | 113 | 1.00 (0.67, 1.50) | 1.39 (0.79, 2.43) |
| Quartile 3 | 322 | 337 | 1.31 (1.04, 1.64) | 1.19 (0.93, 1.53) | 87 | 110 | 0.89 (0.59, 1.35) | 1.00 (0.64, 1.57) |
| Quartile 4 | 335 | 364 | 1.28 (1.01, 1.62) | 1.18 (0.88, 1.58) | 94 | 83 | 1.34 (0.86, 2.11) | 1.02 (0.67, 1.56) |
| P-trend | 0.06 | 0.31 | 0.17 | 0.23 | ||||
aAdjusted for age at selection, sex, ethnicity.
bAdjusted for age at selection, sex, ethnicity, study center, body mass index, level of education, smoking status, physical activity, total energy intake, alcohol intake, fiber intake, dietary calcium, regular use of aspirin or ibuprofen and first-degree family history of colorectal cancer.
*Statistically significant at P < 0.05.