A prospective multicenter evaluation of new fecal occult blood tests in patients undergoing colonoscopy.
ABSTRACT Guaiac-based fecal occult blood (FOB) tests, in particular, Hemoccult II (HO), are commonly used to detect colorectal neoplasia. Because the sensitivity and specificity of these tests are critical to cost-effective screening programs, we aimed to investigate the improved performance characteristics of new FOB tests for known colonic lesions.
Nine centers worldwide performed FOB testing with guaiac-based tests (Hemoccult II [HO] and Hemoccult II SENSA [SENSA]) and immunochemical tests (HemeSelect [HS] and FlexSure OBT [FS]) on 554 patients referred for colonoscopy for predetermined indications. A combination testing strategy consisting of SENSA followed by HS or FS (which was considered positive only when both tests were positive) was also evaluated. Results of FOB tests were compared to findings on colonoscopy.
Cancers were identified in 2.9% of subjects, whereas adenomas > or =10 mm were found in 39 patients. Small adenomas, colitis, and other lesions were identified in 141 patients. The positivity rate of HO for adenomas > or =10 mm was less than for SENSA (20.5% vs 35.9%, p < 0.05), whereas the positivity rate of HO, SENSA, FS, HS, or the combination tests for cancers was not statistically different. The overall positivity rates were significantly greater for FS (15.9%, p = 0.0002) and significantly lower using the combination tests (SENSA/FS 6.0%, p = 0.01; SENSA/HS 6.2%, p = 0.02) compared to HO (9.4%). In this study population, the relative specificity (i.e., true-negative tests/true-negatives + false-positives in patients without adenomas > or =10 mm or cancers) of HO (93.9%; 95% CI, 91.7-96.1) was similar to that of SENSA (92.8%; 95% CI, 90.4-95.2) and HS (90.1%; 95% CI, 87.4-92.8), and greater than FS (88.0%; 95% CI, 85.1-90.9, p < 0.001). When considering adenomas > or =10 mm, cancers alone or cancers and adenomas combined, the combination test using SENSA/FS was associated with significantly fewer false-positive tests than any of the individual tests.
Compared to single tests, the combination test with the highly sensitive SENSA and an immunochemical test had slightly reduced sensitivity but significantly fewer false-positive tests than any single test. These data raise the possibility that a combination test (i.e., highly sensitive guaiac plus immunochemical) could reduce the costs of screening for colon cancer, and suggest that further study of combination test strategies is warranted.
SourceAvailable from: Donald Haverkamp[Show abstract] [Hide abstract]
ABSTRACT: Alaska Native colorectal cancer (CRC) incidence and mortality rates are the highest of any ethnic/racial group in the United States. CRC screening using guaiac-based fecal occult blood tests (gFOBT) are not recommended for Alaska Native people because of false-positive results associated with a high prevalence of Helicobacter pylori-associated hemorrhagic gastritis. This study evaluated whether the newer immunochemical FOBT (iFOBT) resulted in a lower false-positive rate and higher specificity for detecting advanced colorectal neoplasia than gFOBT in a population with elevated prevalence of H. pylori infection. We used a population-based sample of 304 asymptomatic Alaska Native adults aged 40 years or older undergoing screening or surveillance colonoscopy (April 2008-January 2012). Specificity differed significantly (P < .001) between gFOBT (76%; 95% CI, 71%-81%) and iFOBT (92%; 95% CI, 89%-96%). Among H. pylori-positive participants (54%), specificity of iFOBT was even higher (93% vs 69%). Overall, sensitivity did not differ significantly (P = .73) between gFOBT (29%) and iFOBT (36%). Positive predictive value was 11% for gFOBT and 32% for iFOBT. The iFOBT had a significantly higher specificity than gFOBT, especially in participants with current H. pylori infection. The iFOBT represents a potential strategy for expanding CRC screening among Alaska Native and other populations with elevated prevalence of H. pylori, especially where access to screening endoscopy is limited.Preventing chronic disease 04/2014; 11:E56. DOI:10.5888/pcd11.130281 · 1.96 Impact Factor
[Show abstract] [Hide abstract]
ABSTRACT: Background In Taiwan, the prevalence of colorectal cancer has been increasing in recent decades. As a result, the fecal occult blood test (FOBT) has been advocated and widely used for colorectal cancer screening in areas with limited colonoscopy capacity. The goal of this study was to analyze the sensitivity of a single immunochemical FOBT (I-FOBT) and correlate it with the results of colonoscopy for detecting colorectal neoplasia in the asymptomatic Taiwanese population. Methods Data were collected from the results of health examinations conducted on asymptomatic adults older than 40 years and who simultaneously underwent one-time I-FOBT and colonoscopy examinations between January 01, 2008 and June 30, 2009. The sensitivity and specificity of the I-FOBT were calculated in correlation to age, size, and pathologic result. Results A total of 6096 patients were analyzed, including 3418 men and 2678 women, aged 40–87 years. I-FOBT result was positive in 229 patients (3.8%); the sensitivity of detection of total colorectal neoplasia and advanced neoplasia were 6.98% and 22.1%, respectively. A total of 13 participants were found to have invasive cancer in this study, and the sensitivity and specificity of the I-FOBT in this group were 69.2% and 96.4%, respectively. Besides, the positive rate of I-FOBT increased with age, with 40–49 years (2.89%), 50–75 years (4.21%), and >75 years (5.68%). In addition, the sensitivity for detecting total neoplasia and advanced neoplasia was similar in patients ≥50 years and ≥40 years of age. Conclusion The I-FOBT has better sensitivity for detecting invasive cancer and advanced neoplasia than for detecting nonadvanced neoplasia. Repeated I-FOBT examinations with good adherence to the screening program may improve the detection rate and sensitivity of the I-FOBT.09/2014; DOI:10.1016/j.aidm.2013.09.003
[Show abstract] [Hide abstract]
ABSTRACT: To assess the fecal immunochemical test (FIT) accuracy for colorectal cancer (CRC) and advanced neoplasia (AN) detection in CRC screening. We performed a multicentric, prospective, double blind study of diagnostic tests on asymptomatic average-risk individuals submitted to screening colonoscopy. Two stool samples were collected and the fecal hemoglobin concentration was determined in the first sample (FIT1) and the highest level of both samples (FITmax) using the OC-sensor™. Areas under the curve (AUC) for CRC and AN were calculated. The best FIT1 and FITmax cut-off values for CRC were determined. At this threshold, number needed to scope (NNS) to detect a CRC and an AN and the cost per lesion detected were calculated. About 779 individuals were included. An AN was found in 97 (12.5%) individuals: a CRC in 5 (0.6%) and an advanced adenoma (≥ 10 mm, villous histology or high grade dysplasia) in 92 (11.9%) subjects. For CRC diagnosis, FIT1 AUC was 0.96 (95%CI: 0.95-0.98) and FITmax AUC was 0.95 (95%CI: 0.93-0.97). For AN, FIT1 and FITmax AUC were similar (0.72, 95%CI: 0.66-0.78 vs 0.73, 95%CI: 0.68-0.79, respectively, P = 0.34). Depending on the number of determinations and the positivity threshold cut-off used sensitivity for AN detection ranged between 28% and 42% and specificity between 91% and 97%. At the best cut-off point for CRC detection (115 ng/mL), the NNS to detect a CRC were 10.2 and 15.8; and the cost per CRC was 1814€ and 2985€ on FIT1 and FITmax strategies respectively. At this threshold the sensitivity, NNS and cost per AN detected were 30%, 1.76, and 306€, in FIT1 strategy, and 36%, 2.26€ and 426€, in FITmax strategy, respectively. Performing two tests does not improve diagnostic accuracy, but increases cost and NNS to detect a lesion.World Journal of Gastroenterology 01/2014; 20(4):1038-47. DOI:10.3748/wjg.v20.i4.1038 · 2.43 Impact Factor