Aim: To determine calprotectin release before and after colorectal cancer operation and compare it to tumor and histopathological parameters.
Methods: The study was performed on patients with diagnosed colorectal cancer admitted for operation. Calprotectin was measured in a single stool sample before and three months after the operation using an enzyme-linked immunosorbent assay (ELISA). Calprotectin levels greater than or equal to 50 μg/g were considered positive. The compliance for collecting stool samples was assessed and the value of calprotectin was correlated to tumor and histopathological parameters of intra- and peri-tumoral inflammation. Surgical specimens were fixed in neutral buffered formalin and stained with hematoxylin and eosin. Staging was performed according to the Dukes classification system and the 7(th) edition tumor node metastasis classification system. Intra- and peri-tumoral inflammation was graded according to the Klintrup criteria. Immunohistochemical quantification was performed for MPO, CD45R0, TIA-1, CD3, CD4, CD8, CD57, and granzyme B. Statistical significance was measured using Wilcoxon signed rank test, Kruskal Wallis test and Spearman's rank correlation coefficient as appropriate.
Results: Between March 2009 and May 2011, 80 patients with colorectal cancer (46 men and 34 women, with mean age of 71 ± 11.7 years old) were enrolled in the study. Twenty-six patients had rectal carcinoma, 29 had left-side tumors, 23 had right-side tumors, and 2 had bilateral carcinoma. In total, 71.2% of the patients had increased levels of calprotectin before the operation (median 205 μg/g, range 50-2405 μg/g) and experienced a significant decrease three months after the operation (46 μg/g, range 10-384 μg/g, P < 0001). The compliance for collecting stool samples was 89.5%. Patients with T3 and T4 tumors had significantly higher values than those with T1 and T2 cancers (P = 0.022). For all other tumor parameters (N, M, G, L, V, Pn) and location, no significant difference in calprotectin concentration was found. Furthermore, the calprotectin levels and histological grading of both peri- and intra-tumoral inflammation was not correlated. Additional testing with specific markers for lymphocytes and neutrophils also revealed no statistically significant correlation.
Conclusion: Fecal calprotectin decreases significantly after colorectal cancer operation. Its value depends exclusively on the individual T-stage, but not on other tumor or histopathological parameters.
Keywords: Calprotectin; Colorectal cancer; Granulocytes; Inflammation; Tumor size.