Colorectal cancer in iron deficiency anemia with a positive result on immunochemical focal occult blood

We examined the relationships between iron deficiency anemia, immunochemica l fecal occult blood test results, and colorectal cancer. Samples were coll ected from 17,664 asymptomatic individuals for an immunochemical occult blo od test, and colonoscopy was carried out during medical check-up. The posit ivity rate on the occult blood test and detection rate for colorectal cance r were compared in those with and those without iron deficiency anemia. In addition, the detection rate for colorectal cancer was determined in four g roups stratified by occult blood test results and the presence of iron defi ciency anemia. The occult blood test was positive in 18.4% of those with an d in 3.8% of those without iron deficiency anemia (P<0.001), and colorectal cancer wasdetected in 2.7% of those with and in 0.4% of those without iron deficiency anemia (P<0.05). The highest rate of colorectal cancer was foun d in subjects with both iron deficiency anemia and positive occult blood te st result. These findings indicate positive associations between iron defic iency anemia and immunochemical occult blood test results, and between iron deficiency anemia and colorectal cancer. Colonoscopy is thus necessary par ticularly in cases of positive immunochemical occult blood test result and iron deficiency anemia.