Low serum ferritin levels as a clue to colonic cancer detection in two patients with coronary artery disease: a case report.

We diagnosed colonic cancer using low serum ferritin levels as a clue in two patients with cardiac or cardiopulmonary disease. In the course of the follow-up, the serum ferritin levels decreased to less than 18 ng/mL without significant appearance of iron-deficiency anemia. One patient showed positive immunological fecal occult blood test results whereas the other not. Both patients rejected further colonoscopy because of their concern for stress in relation to their cardiac or cardiopulmonary diseases, but instead agreed to positron emission computed tomography (PET) using a F-18 deoxyglucose at their own expense. In both patients, PET documented abnormal tracer accumulation in the colon. From the results of PET imaging, they eventually agreed to colonoscopy. A colonic adenocarcinoma was detected at the site of the positive PET finding in each patient. Both patients underwent curative resection of the cancer. The detection of the levels of serum ferritin may be available for the screening colonic cancer in patients declining colonoscopic examination.