Fecal calprotectin and fecal occult blood tests in diagnosis of colorectal neoplasia
Fecal calprotectin vs. fecal occult blood tests
A report published in the journal Gut compares fecal calprotectin and fecal occult blood testing as methods for detection of colorectal carcinoma and adenoma.
Testing for fecal occult blood has become an accepted technique of non-invasive screening for colorectal neoplasia but lack of sensitivity remains a problem.
A comparison of the sensitivity and specificity of fecal calprotectin and fecal occult blood in patients with colorectal cancer and colonic polyps has therefore been conducted by a research team from England and Norway.
Fecal calprotectin and occult blood were assessed in 62 patients with colorectal carcinoma, and 233 patients referred for colonoscopy.
The range of normality for fecal calprotectin (0.5-10.5 mg/l) was determined from 96 healthy subjects.
Median fecal calprotectin concentration in the 62 patients with colorectal carcinoma (101 mg/l, 95% confidence interval (CI) 57-133) differed significantly from normal (2.3 mg/l, 95% CI 1.6-5.0).
Within this group, 90% of patients had elevated levels (normal <10 mg/l), whereas only 36/62 (58%) had positive fecal occult bloods.
There was no significant difference in fecal calprotectin levels when considering location or Dukes' staging of tumor.
Percentage positivity of fecal occult bloods was significantly higher for Dukes' stage C and D cancers compared with Dukes' A and B.
In the colonoscopy group, 29 patients with adenomatous polyps were detected in whom the median fecal calprotectin was 12 mg/l (95% CI 2.9-32).
more sensitive than fecal occult blood tests
Sensitivity for detection of adenomatous polyps was 55% using the calprotectin method and 10% using fecal occult blood testing.
The overall sensitivity and specificity of calprotectin for colorectal cancer and adenomatous polyps as a combined group was 79% and 72%, respectively, compared with a sensitivity and specificity of fecal occult blood of 43% and 92%.
J Tibble, concluding on behalf of his fellow authors, described fecal calprotectin as "a simple and sensitive non-invasive marker of colorectal cancer and adenomatous polyps."
He added, "It is more sensitive than fecal occult blood tests for detection of colorectal neoplasia, although at the cost of a somewhat lower specificity."