Clinical Question: Are patients with iron deficiency anemia at increased risk of also having a gastrointestinal (GI) malignancy?

Setting: Population-based

Study Design: Cohort (prospective)

Synopsis: The investigators started with 9,024 adults (mean age: 40 years) who were enrolled in a general study of health and nutrition. Eight percent of these patients had iron deficiency (determined by iron saturation of less than 15 percent), and 1.6 percent of the total group also was anemic. A GI malignancy was identified during the following two years in 18 patients (0.2 percent). None of the premenopausal women with iron deficiency was anemic (95 percent confidence interval [CI]: 0 to 3 percent). Among patients with iron deficiency anemia, one in 16 (6 percent, 95 percent CI: 1 to 16 percent) was diagnosed with a GI malignancy during the subsequent two years. Of patients older than 65 years, 9 percent (95 percent CI: 2 to 25 percent) with anemia had a malignancy. Only 1 percent of the patients with iron deficiency but without anemia developed a malignancy. The rate of GI malignancy in patients without iron deficiency or anemia was 0.3 percent. These numbers should be reassuring to clinicians who care for premenopausal women; a previous study has identified a risk of about 6 percent in a more highly selected population. The data confirm other research that has shown a high rate of malignancy in older patients.

Bottom Line: Older patients with iron deficiency anemia are 31 times more likely than the general population to have a GI malignancy. Six percent of patients older than 50 years and one in 11 patients older than 65 years will be diagnosed with a malignancy within two years. Iron deficiency anemia in older patients should alert physicians to perform further GI testing. (Level of Evidence: 1b)