Background: Fecal calprotectin is elevated in patients with colorectal cancer (CRC). An improved method has been developed. The aim was to evaluate sensitivity and specificity for CRC with the new fecal calprotectin method and to compare the results with those of the original method.
Methods: The study comprised 453 subjects including symptomatic CRC patients and CRC high risk subjects with and without CRC. Complete colonoscopy was performed. Calprotectin was measured with an enzyme linked immunosorbent assay (ELISA) using small (50-100 mg) feces samples.
Results: Fecal calprotectin levels were significantly elevated in symptomatic CRC and in asymptomatic CRC detected in high risk subjects. Calprotectin levels were significantly decreased 3 months after cancer removal. A cut-off limit of 50 microg/g resulted in a sensitivity of 89% in CRC patients and 79% in high risk subjects, compared to 89% and 75%, respectively, with the original method, using 10 mg/l as cut-off limit. Specificity was improved with the new method to 68% and 91% at cut-off of 50 and 150 microg/g, compared to 66% and 88%, respectively. Negative predictive value (NPV) was 99% for cut-off of 50 microg/g in the high risk population. One stool sample was sufficient, but measurement of two spots in two stools increased sensitivity to 98% for symptomatic and 82% for asymptomatic CRC.
Conclusion: The new simple method, using small samples of feces, had a higher diagnostic accuracy, suggesting that it should be preferred to the original one, in screening high risk groups for CRC.