Fecal excretion of calprotectin in colorectal cancer: Relationship to tumor characteristics

The aim of this study was to evaluate fecal calprotectin in patients treated for colorectal cancer. Furthermore, the changes in fecal calprotectin concentration from before to after surgery were investigated. In 155 patients with newly diagnosed colorectal cancer, two spot samples were taken from the same feces on two consecutive days. Three ways of evaluating calprotectin excretion were compared, (1st spot 1st stool; maximum of 1st spot 1st stool and 2nd spot 1st stool; maximum of 1st spot 1st stool and 1st spot 2nd stool) and gave similar results with median fecal calprotectin values 47 mg/l, 52 mg/l and 54 mg/l, respectively. Median calprotectin concentration did not differ significantly between different tumor stages, although the levels were slightly lower in Dukes stage A tumor than in the rest of the stages. Neither were there any differences in the concentrations related to the localization, size or the histological grading of the carcinoma. As the currently used cut-off level for fecal calprotectin is 10 mg/l, 87% of all patients had elevated fecal calprotectin. Seventy-nine percent of the patients had levels above 15 mg/l and 74% had levels above 20 mg/l (1st spot 1st stool). In patients who delivered fecal samples after the operation the calprotectin value fell significantly from a preoperative median value of 45 mg/l to 14 mg/l after the resection. The majority of patients with colorectal cancer have increased fecal concentration of calprotectin. One single fecal spot seems to be sufficient for determination of the calprotectin level. Measurement of fecal calprotectin may possibly become of value as a marker for colorectal cancer, although calprotectin, similar to fecal occult blood (FOB) tests, is a non-specific test for colorectal pathology, also being elevated in inflammatory bowel diseases. Further investigation of its specificity is therefore needed.