Clinicopathologic significance of immunohistochemical fecal occult blood test in subjects receiving bidirectional endoscopy.
OBJECTIVE
Fecal occult blood test has been utilized to screen for lower gastrointestinal pathologies, such as colorectal cancer and polyps that bleed. Recent studies have revealed a relatively high frequency of upper gastrointestinal abnormalities in subjects with positive fecal occult blood by guaiac-based method. Although immunohistochemical tests of fecal occult blood were assumed to have greater diagnostic validity, the distribution of gastrointestinal pathology using such examinations is not well established. This study aims to investigate the efficacy of immunohistochemical analysis of fecal occult blood in detecting upper and lower gastrointestinal lesions in asymptomatic individuals.


METHODS
Subjects who underwent regular health checkups were enrolled if they received both esophagogastroscopic and colonoscopic examinations. Each subject was tested by an immunohistochemical fecal occult blood test. The fecal occult blood results were evaluated and correlated with lesions identified in endoscopic examinations.


RESULTS
In total 655 males and 722 females with age 46.2 +/- 12.1 years were enrolled, 287 cases (20.7%) had polypoid lesions of colon, including 6 colon cancers, 37 with polyps > or = 1 cm, 104 with polyp 5-9 mm, and 140 with polyp < 5 mm. FOB was positive in 31 cases, of which 15 (15/31, 48.4%) were polypoid lesions of colon, 1 was colonic ulcer, 9 (29.0%) were active gastroduodenal ulcers but 6 (19.4%) had no significant lesions. The positive and negative predictive value for colon polyps was 48.4% and 80%, respectively. The sensitivity was 50% (3/6) for colon cancer and varied among polyps with different sizes: 16.2% (6/37) for polyps > or = 1 cm; 5.8% (6/104) for polyps 5-9 mm and 0% (0/140) for polyps < 5 mm.


CONCLUSIONS
A substantial portion of subjects (29%) with positive fecal occult blood reaction of immunohistochemical analysis but negative colonoscopy still needs esophagogastroscopic examination to disclose upper gastrointestinal lesions. Immunohistochemical determination of fecal occult blood remains imperfect for polypoid lesions of colon in view of its sensitivity and specificity.
Graduate Institute of Public Health, Taipei Medical College, Taipei, Taiwan.
Hui-Hsiung
HH
Liu
Thomas W
TW
Huang
Hsiao-Ling
HL
Chen
Teh-Hong
TH
Wang
Jaw-Town
JT
Lin
D003110:Colonic Neoplasms / Q000175:diagnosis; D003111:Colonic Polyps / Q000175:diagnosis; D003113:Colonoscopy; D016145:Endoscopy, Digestive System; D005260:Female; D005767:Gastrointestinal Diseases / Q000175:diagnosis*; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009780:Occult Blood; D012680:Sensitivity and Specificity