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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.

Fecal calprotectin (CPT) is elevated in the majority of patients with known colorectal cancer (CRC), but the specificity is not clarified. Aim: To evaluate if a CPT test (PhiCal ELISA) was more sensitive than Hemoccult II test in detecting colorectal neoplasia, and to obtain reference values in subjects with normal colonoscopy. To evaluate a possible relation between number and extent of dysplasia of adenomas in first degree relatives of patients with CRC and the stage of the carcinoma in the index casus. Further to study the prevalence of CRC and adenomas in the first degree relatives of patients operated for CRC. Method: In a multicenter study, 253 first degree relatives of patients with CRC, aged 50–75 years (mean age 60 years) underwent colonoscopy after having delivered stool samples and three Hemoccult II slides. Results: In 237 first degree relatives from 148 patients with CRC, polyps were found in 118 (50%). Seventy three (31%) had adenomas and 17 had adenomas ≧10 mm. Five had asymptomatic cancers. The specificity of fecal CPT for adenomas at cut off levels ≤10, ≤15 and ≤20 mg/l were 47.4, 59.6 and 71.1%, respectively (max of three samples). The sensitivity at same cut off levels was 56.2, 45.2 and 31.5% and 4/5 of patients with carcinoma had CPT values >15 mg/l. The sensitivity of Hemoccult II for adenomas was 8%, and 4/5 of patients with carcinoma had negative Hemoccult II. The specificity for adenomas was 95%. Conclusion: Fecal CPT test was more sensitive than Hemoccult II in detecting colorectal neoplasia but the specificity was lower. In a high risk group like first degree relatives of patients with CRC, there are good reasons to consider fecal CPT as a first test in selecting patients for endoscopy.

Day-to-day variation of fecal calprotectin is considerable in patients without colonic inflammation or neoplasm, for whom the pattern of stabile low fecal calprotectin may seem to be a valid negative predictor. The origin and pattern of fecal calprotectin excretion deserve further attention.

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