Screening for colorectal neoplasms with new fecal occult blood tests: update on performance characteristics.
BACKGROUND
One type of fecal occult blood test (FOBT), the unrehydrated guaiac fecal occult blood test (GT), is recommended by the United States Preventive Services Task Force and the Institute of Medicine for use in screening programs, but it has relatively low sensitivity as a single test for detecting advanced colonic neoplasms (cancer and adenomatous polyps > or = 1 cm in diameter). Thus, improving the sensitivity of FOBT should make colon cancer screening programs that use these tests more effective.


METHODS
We assessed prospectively the performance characteristics of two newer FOBTs in 5841 subjects at average risk for colorectal cancer in a large group-model managed care organization. The tests evaluated included a sensitive GT, a fecal immunochemical test (FIT), and the combination of both tests. Patients with positive and negative test results were advised to have colonoscopy and sigmoidoscopy, respectively. Sensitivity and specificity for detecting advanced neoplasms in the left colon within 2 years after the FOBT screening were evaluated for the two tests administered separately and in combination.


RESULTS
A total of 139 patients were diagnosed with advanced colorectal neoplasms (n = 14 cancers, n = 128 adenomas) within the 2 years following their initial FOBT screening. Sensitivity for detecting cancer was 81.8% (95% confidence interval [CI] = 47.8% to 96.8%) for the FIT alone and 64.3% (95% CI = 35.6% to 86.0%) for the sensitive GT and the combination test. Sensitivity for detecting advanced colorectal adenomas was 41.3% (95% CI = 32.7% to 50.4%) for the sensitive GT, 29.5% (95% CI = 21.4% to 38.9%) for the FIT, and 22.8% (95% CI =16.1% to 31.3%) for the combination test. Specificity for detecting cancer and adenomas was 98.1% (95% CI = 97.7% to 98.4%) and 98.4% (95% CI = 98.0% to 98.7%), respectively, for the combination test; 96.9% (95% CI = 96.4% to 97.4%) and 97.3% (95% CI = 96.8% to 97.7%), respectively, for the FIT; and 90.1% (95% CI = 89.3% to 90.8%) and 90.6% (95% CI = 89.8% to 91.4%), respectively, for the sensitive GT.


CONCLUSIONS
The FIT has high sensitivity and specificity for detecting left-sided colorectal cancer, and it may be a useful replacement for the GT.
Allison
James E
JE
Division of Research, Kaiser Permanente Northern California Region, 2000 Broadway, Oakland, CA 94612-2304, USA. jea@dor.kaiser.org
Sakoda
Lori C
LC
Levin
Theodore R
TR
Tucker
Jo P
JP
Tekawa
Irene S
IS
Cuff
Thomas
T
Pauly
Mary Pat
MP
Shlager
Lyle
L
Palitz
Albert M
AM
Zhao
Wei K
WK
Schwartz
J Sanford
JS
Ransohoff
David F
DF
Selby
Joseph V
JV
D000368:Aged; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000175:diagnosis / Q000517:prevention & control*; D005243:Feces / Q000737:chemistry*; D005260:Female; D006138:Guaiac; D006801:Humans; D007120:Immunochemistry; D007202:Indicators and Reagents; D008297:Male; D008403:Mass Screening / Q000379:methods*; D008875:Middle Aged; D009780:Occult Blood; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D012812:Sigmoidoscopy; D014481:United States
D007202:Indicators and Reagents; D006138:Guaiac