Serum Chemerin Concentrations and Tissue Immunoreactivity in Colorectal Adenoma and Colorectal Cancer: An Exploratory Case–Control Study

Background/Objectives: Chemerin is an adipokine implicated in metabolic regulation, inflammation and cancer biology, but its value as a circulating biomarker in colorectal neoplasia remains uncertain. We investigated serum chemerin concentrations in patients with colorectal cancer (CRC), patients with colorectal polyps and colonoscopy-negative controls, and explored chemerin immunoreactivity in available polyp and tumour tissue. Methods: This exploratory observational case–control study included 41 patients with CRC, 20 patients with colorectal polyps and 29 colonoscopy-negative controls. Serum chemerin was measured by ELISA. Tissue specimens underwent routine histopathology and qualitative immunohistochemical staining for chemerin. Between-group comparisons were performed using non-parametric tests; subgroup analyses were exploratory and unadjusted. Results: Serum chemerin concentrations did not differ significantly between CRC and controls (median 144.0 vs. 135.7 ng/mL; p = 0.41), CRC and polyp groups (144.0 vs. 97.4 ng/mL; p = 0.24), or polyp and control groups (97.4 vs. 135.7 ng/mL; p = 0.94). Chemerin immunostaining was absent in CRC tissue (0/41) and conventional adenomatous polyps (0/15), whereas all available hyperplastic/serrated lesions showed epithelial cytoplasmic and/or stromal immunoreactivity (5/5); in lesions containing dysplasia, dysplastic glands showed no detectable staining. In controls, higher chemerin concentrations were associated with hyperglycaemia, hypertension, body weight and bilirubin, but these exploratory findings were not adjusted for multiplicity or metabolic confounding. Conclusions: In this exploratory cohort, serum chemerin did not discriminate CRC or colorectal adenoma from colonoscopy-negative controls. Together with the absence of staining in CRC and conventional adenomas, the findings argue against chemerin as a standalone circulating or commonly expressed tissue biomarker for these lesions under the assay conditions used. Immunoreactivity in the non-dysplastic epithelial and/or stromal compartments of hyperplastic/serrated lesions remains preliminary and requires prospective confirmation with standardised pre-analytics, quantitative pathology scoring and adjustment for metabolic confounders.