Wurzelmann J I, Silver A, Schreinemachers D M, Sandler R S, Everson R B
Division of Digestive Diseases, University of North Carolina, Chapel Hill 27599-7038, USA.
Cancer Epidemiol Biomarkers Prev. 1996 Jul;5(7):503-7.
Prospectively gathered data from the National Health and Nutrition Examination Survey I and the National Health Evaluation Follow-Up Study were analyzed to evaluate the risk of colorectal cancer due to consumption of iron. Morbidity and mortality data due to colorectal cancer were available on 14,407 persons first interviewed in 1971 and followed through 1986. A total of 194 possible colorectal cancers occurred in this group over the 15-year period. Subsite analysis showed that the risk of colon cancer due to iron intake was elevated throughout the colon for both men and women, with the highest adjusted risks for the interquartile range seen in the proximal colon for females (relative risk, 1.51; 95% confidence interval, 1.41-1.60). The risk of rectal cancer was not significantly elevated for men or women. Elevated serum iron was also associated with increased risk; however, this effect was strongest in the distal (rather than proximal) colon and was significant only among females (adjusted relative risk, 1.73; 95% confidence interval, 1.03-2.92). The mean transferrin saturation was higher among cases than controls (30.7 versus 28.7%), but total iron-binding capacity did not seem to predict the occurrence of colorectal cancer. Proportional hazards models confirmed that the effects of iron and serum iron were not confounded by age, gender, energy consumption, fat intake, or other known risk factors for colorectal cancer. These data suggest that iron may confer an increased risk for colorectal cancer, and that the localization of risk may be attributable to the mode of epithelial exposure. It seems that luminal exposure to iron increases risk proximally, whereas humoral exposure increases risk distally. These differences may be due to such factors as oxidation state, binding proteins and the presence of other cofactors such as bile acids, products of bacterial metabolism.
对前瞻性收集的来自第一次全国健康和营养检查调查及全国健康评估随访研究的数据进行了分析，以评估因摄入铁而患结直肠癌的风险。有14407人的结直肠癌发病和死亡数据，这些人于1971年首次接受访谈，并随访至1986年。在这15年期间，该组共发生了194例可能的结直肠癌。亚部位分析显示，男性和女性因铁摄入导致的结肠癌风险在整个结肠均有所升高，女性近端结肠四分位数间距的调整后风险最高（相对风险，1.51；95%置信区间，1.41 - 1.60）。男性和女性的直肠癌风险均未显著升高。血清铁升高也与风险增加有关；然而，这种影响在远端（而非近端）结肠最为明显，且仅在女性中显著（调整后相对风险，1.73；95%置信区间，1.03 - 2.92）。病例组的平均转铁蛋白饱和度高于对照组（30.7%对28.7%），但总铁结合能力似乎不能预测结直肠癌的发生。比例风险模型证实，铁和血清铁的影响不受年龄、性别、能量消耗、脂肪摄入或其他已知的结直肠癌风险因素的混杂。这些数据表明，铁可能会增加患结直肠癌的风险，风险的定位可能归因于上皮暴露的方式。似乎腔内铁暴露会增加近端风险，而体液暴露会增加远端风险。这些差异可能归因于氧化状态、结合蛋白以及其他辅助因子如胆汁酸、细菌代谢产物的存在等因素。
