Comparison of guaiac-based and quantitative immunochemical fecal occult blood testing in a population at average risk undergoing colorectal cancer screening.
OBJECTIVE
Although some studies have shown that the quantitative, immunochemical fecal occult blood test (FOBT) (qFIT) has better performance characteristics than the standard guaiac-based FOBT (GT) for identifying advanced colorectal neoplasia (ACRN), there is limited information on test performance of these tests in average-risk populations.


METHODS
Seven hundred seventy consecutive average-risk patients from four centers who were undergoing screening colonoscopy also provided stool samples. Stool specimens from three consecutive bowel movements were applied to a hemoccult II test card (Beckman Coulter, Fullerton, CA) and OC-SENSA MICRO (Eiken Chemical, Tokyo, Japan) sampling probes at the same time. We measured the diagnostic value of the qFIT for detecting an ACRN by using three criteria: sensitivity, specificity, and likelihood ratios. A receiver operating characteristic curve for determining the qFIT cutoff values and the number of tests that best discriminated between ACRNs and other findings were determined.


RESULTS
Seventy-eight ACRNs were identified during colonoscopy. At all hemoglobin thresholds, the sensitivity of the qFIT was higher than that of the GT for cancer or ACRN. The sensitivity and specificity of the GT for detecting advanced adenomas, cancer, and ACRNs were 13.6%/92.4%, 30.8%/92.4%, and 16.7%/92.9%, respectively. Using the 100 ng/ml cut point and three-sample qFIT results, the sensitivity and specificity of the qFIT for detecting advanced adenomas, cancer, and ACRNs were 33.9%/90.6%, 84.6%/89.8%, and 43.7%/91.9%, respectively. The area under the curve for cancer indicated that using either 2 or 3 tests provided the best discrimination for cancer.


CONCLUSIONS
The qFIT provides a higher sensitivity for detecting ACRN and cancer than the GT, and has an acceptable specificity that significantly reduces the need for colonoscopic evaluation in the screened population.
Park
Dong Il
DI
Department of Internal Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea.
Ryu
Seungho
S
Kim
Young-Ho
YH
Lee
Suck-Ho
SH
Lee
Chang Kyun
CK
Eun
Chang Soo
CS
Han
Dong Soo
DS
D000236:Adenoma / Q000175:diagnosis*; D000368:Aged; D019540:Area Under Curve; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000175:diagnosis*; D055088:Early Detection of Cancer / Q000379:methods*; D005260:Female; D006138:Guaiac; D006801:Humans; D007120:Immunochemistry; D008297:Male; D008875:Middle Aged; D009780:Occult Blood; D011237:Predictive Value of Tests; D012372:ROC Curve; D012307:Risk Factors; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric
D006138:Guaiac