Iron deficiency and gastrointestinal malignancy: a population-based cohort study.
OBJECTIVE
We investigated whether iron deficiency, with or without anemia, is associated with an increased likelihood of gastrointestinal malignancy.


METHODS
Data were obtained from the first National Health and Nutrition Examination Survey and Epidemiologic Followup Study, a nationally representative, prospective cohort study that measured hemoglobin levels and iron saturation and recorded follow-up diagnoses. We included persons 25 to 74 years of age with no previous gastrointestinal malignancy. Anemia was defined as a hemoglobin value below the fifth percentile for each age group and sex. Iron deficiency was defined as an iron saturation below 15%.


RESULTS
Eighteen (0.2%) gastrointestinal malignancies were identified among the 9024 participants during the first 2 years of follow-up. None of the 442 premenopausal women with iron deficiency (92 with anemia and 350 without anemia) were diagnosed with gastrointestinal malignancy. Among men and postmenopausal women, the proportion diagnosed with gastrointestinal malignancy was 31 times greater (95% confidence interval [CI]: 9 to 107) in those with iron deficiency anemia (3/51 [6%]) and five times greater (95% CI: 1 to 21) in those with iron deficiency without anemia (2/223 [1%]), compared with those with normal hemoglobin levels and iron saturation (11/5733 [0.2%]).


CONCLUSIONS
Gastrointestinal malignancy is uncommon in iron-deficient premenopausal women with or without anemia. Among men and postmenopausal women, gastrointestinal malignancy is significantly more common in those with iron deficiency than in persons with normal serum iron saturation and hemoglobin levels.
D000328:Adult; D000367:Age Factors; D000368:Aged; D018798:Anemia, Iron-Deficiency / Q000150:complications / Q000453:epidemiology*; D015331:Cohort Studies; D005260:Female; D005770:Gastrointestinal Neoplasms / Q000150:complications / Q000453:epidemiology*; D006454:Hemoglobins; D006801:Humans; D000090463:Iron Deficiencies; D008297:Male; D008403:Mass Screening / Q000379:methods; D008875:Middle Aged; D009749:Nutrition Surveys; D009780:Occult Blood; D017698:Postmenopause; D011446:Prospective Studies; D012737:Sex Factors; D014481:United States / Q000453:epidemiology
D006454:Hemoglobins