Preprint version. Cancer Epidemiology, Biomarkers & Prevention, Volume 9, June 1, 2000, pages 625-630. Copyright © 2000 American Association for Cancer Research.
NOTE: At the time of publication, the author Marilyn Tseng was not yet affiliated with Cal Poly.
Abstract Both body iron stores and dietary iron intake have been reported to increase risk of colorectal neoplasms. We assessed whether serum ferritin concentration was associated with recurrence of colorectal adenomas among 733 individuals with baseline determinations of ferritin as part of a multicenter clinical trial of antioxidant supplements for adenoma prevention. All study participants had at least one adenoma removed within 3 months before enrollment, and 269 of them developed one or more adenomas between follow-up colonoscopies conducted 1 and 4 years after enrollment. Baseline serum ferritin concentrations were analyzed both as a log-transformed continuous variable and as a categorical variable, defined as whether iron stores were nonreplete and low (ferritin ≤30 μg/liter), nonreplete and borderline (31–70 μg/liter), replete and adequate (71–160 μg/liter), or replete and high (>160 μg/liter). Analyses were based on multiple logistic regression models, including age, sex, study center, energy, alcohol, fiber, folate, and total fat intake, number of months between colonoscopic examinations, smoking status, and aspirin use. Overall, there was no statistically significant linear association between log ferritin concentration and adenoma recurrence (P = 0.33). Risk of adenoma recurrence was modestly increased among participants with ferritin concentrations >70 μg/liter relative to those with lower ferritin (odds ratio, 1.39; 95% confidence interval, 0.96 – 2.02). This result seemed more pronounced among women than men. Dietary intake of iron and red meat was inversely associated with adenoma recurrence among participants with replete iron stores but not consistently associated among those with nonreplete stores. Our findings suggest that any role of iron stores and dietary iron in influencing risk of colorectal adenoma recurrence is likely complex.