Many expert panels recommend colorectal cancer screening for average-risk asymptomatic individuals older than 50 years of age.
Recent studies have found that 24% to 64% of primary care providers use only the digital fecal occult blood test (FOBT) as their primary screening test.
The effectiveness of a single digital fecal occult blood test is unknown.
Dr Collins and colleagues from Oregon undertook a prospective cohort study to compare the sensitivity and specificity of digital FOBT and the recommended 6-sample at-home FOBT for advanced neoplasia in asymptomatic persons.
The researchers enrolled a total of 3,121 asymptomatic patients from 50 to 75 years of age from 13 Veterans Affairs medical centers.
The research team gave 2,665 patients 6-sample at-home FOBT and digital FOBT, followed by complete colonoscopy.
The researchers measured the sensitivity of digital and 6-sample FOBT for advanced neoplasia and the specificity for no neoplasia.
In addition, the researchers calculated predictive values and likelihood ratios for advanced neoplasia, defined as tubular adenomas 10 mm or greater, adenomas with villous histology or high-grade dysplasia, or invasive cancer.
|Detection of advanced neoplasia in 284 patients was 24% for the 6-sample FOBT and 5% for the digital FOBT|
|Annals of Internal Medicine|
Of all participants, 97% were men; their average age was 63 years.
The research team found that the 6-sample FOBT and the single digital FOBT had specificities of 94% and 98%, respectively, as defined by studying 1656 patients with no neoplasia.
Sensitivities for detection of advanced neoplasia in 284 patients were 24% for the 6-sample FOBT and 5% for the digital FOBT.
The likelihood ratio for advanced neoplasia was 1.7 for positive results on digital FOBT and 0.98 for negative results.
Dr Collins concluded, "Single digital FOBT is a poor screening method for colorectal neoplasia and cannot be recommended as the only test."
"When digital FOBT is performed as part of a primary care physical examination, negative results do not decrease the odds of advanced neoplasia."
"Persons with these results should be offered at-home 6-sample FOBT or another type of screening test."