Background. False positives of fecal occult blood tests (FOBT) regarding colorectal cancer detection are common. The aim was to investigate the upper gastrointestinal (GI) condition confirmed by endoscopy in positive FOBT patients without advanced colorectal neoplasia, hemorrhoid, or colitis. Methods. The authors reviewed the collective data of 340 positive FOBT patients who underwent both esophagogastroduodenoscopy (EGD) and colonoscopy from January 2005 to October 2011. Demographic data, effects of medications, including antiplatelet agents, nonsteroidal anti-inflammatory drugs, or warfarin on the results of FOBT, presence or absence of GI mucosal lesions confirmed by EGD and colonoscopy, and FOBT titer in 552 positive FOBT patients were analyzed. Results. On colonoscopy, colorectal cancer was detected in 35 patients (10.3%), advanced adenoma in 22 patients (6.4%). "Negative colonoscopy" included no significant lesions and non-advanced adenomas. In 243 patients with "negative colonoscopy", EGD findings included 3 (1.2%) gastric cancers and 39 (16%) peptic ulcer diseases. Gastric cancers were all found in patients who had no experience of EGD within 2 years; however, the incidence of peptic ulcer disease was not different in patients with or without previous EGD within 2 years. Two or more antiplatelet agents increased false positive rates of FOBT. Conclusions. Upper GI evaluation is mandatory in patients with positive FOBTs and negative colonoscopy especially in patients without experience of EGD within 2 years.
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