Evaluation of Calgranulin B in Stools from the Patients with Colorectal Cancer

PURPOSE: Calprotectin (heterodimer of calgranulin A and B) has been previously studied as a candidate stool marker for detecting colorectal cancer. We assessed the clinical usefulness of calgranulin B as a stool marker for colorectal cancer in a pilot study of patients with colorectal cancer. METHODS: We performed 2-DE-based proteomics to screen stool markers for colorectal cancer. We checked the calgranulin B in stools from 77 colorectal cancer patients and from 75 controls by western blot and enzyme-linked immunosorbent assay. We measured calgranulin A using the same methods, and stool hemoglobin by immunologic fecal occult blood test. RESULTS: Fecal calgranulin A did not show any difference, but stool calgranulin B of colorectal cancer patients was significantly higher than controls [50.6 ng/mg stool protein (SD, 34.8) vs. 20.2 ng/mg stool protein (SD,24.0), respectively, P < 0.001). At the cut off level 24.4 ng/mg stool protein, the sensitivity was somewhat higher than fecal occult blood test (72.0 percent vs. 62.3 percent) but the specificity was much lower than fecal occult blood test (77.1 percent vs. 98.7 percent). CONCLUSIONS: Calgranulin B was increased in stools of colorectal cancer patients but our results suggest that colorectal cancer screening by determination of stool calgranulin B would not be better than conventional fecal occult blood test.