Introduction:
Patients with iron deficiency anemia (IDA) are more likely than the general population to have an underlying gastrointestinal malignancy, with prior literature suggesting 8.9% have a lower gastrointestinal (GI) malignancy found by colonoscopy and 2.0% have an upper GI malignancy found by upper endoscopy. Therefore, the American Gastroenterological Association guideline on the evaluation of iron deficiency anemia recommends that all postmenopausal women and men with iron deficiency anemia undergo a bidirectional endoscopy. However, little is known about the compliance rates of bidirectional endoscopy completion for patients with iron deficiency anemia. This study therefore sought to characterize how many patients with iron deficiency anemia complete the recommended cancer screening and how many patients develop a new diagnosis of gastrointestinal malignancy.

Methods:
Study population consisted of patients diagnosed with iron deficiency anemia between January 2020 and June 2023 at a large academic medical center. Iron deficiency anemia was diagnosed by a ferritin value less than 45. Patients below the age of 60 were excluded. Compliance rates were calculated as the completion rate of bidirectional endoscopy, meaning both an upper endoscopy and colonoscopy within 1 year of iron deficiency anemia diagnosis. Cancer diagnosis was calculated as a new diagnosis of gastrointestinal malignancy including esophageal cancer, colon cancer, rectosigmoid cancer, rectal cancer, or anal cancer within 2 years of iron deficiency anemia diagnosis.

Results:
1343 patients were included with a median age of 71. 59.9% were female. There was an average completion rate of 27.8% for upper endoscopy, 31.4% for colonoscopy, and 19.7% for both. Of patients who had not completed a bidirectional endoscopy, 71.6% of patients were due for both an endoscopy and a colonoscopy, while 17.1% were due for just an upper endoscopy and 11.3% were due for just a colonoscopy. Within 2 years of IDA diagnosis based on a ferritin < 45, 61 patients (4.5%) went on to develop gastrointestinal cancer, with 45 cases (3.4%) of colon cancer, 8 cases (0.6%) of rectal cancer, 3 cases (0.2%) of esophageal cancer, 3 cases (0.2%) of anal cancer, and 2 cases (0.1%) of rectosigmoid cancer.

Discussion:
Among patients with iron deficiency anemia, 4.5% went on to develop a new diagnosis of gastrointestinal malignancy within 2 years. Efforts to increase rates of compliance with AGA guideline recommendations for bidirectional endoscopies among patients with iron deficiency anemia have the potential to reduce the rate of new cancer diagnoses.

Rachel Porth

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