Serumtest für C3a Anaphylatoxin ermöglicht minimal-invasives Screening für kolorektale Tumoren

Abstract

Background: Late diagnosis of colorectal carcinomas results in a significant reduction of average survival times. However, despite screening programs, about 70 % of tumors are detected at advanced stages (UICC III/IV). We therefore aimed at detecting tumor-specific protein biomarkers in serum samples that could potentially be applied for early diagnostics. Methods: A discovery set of sera from patients with colorectal malignancy (n = 58) and healthy control individuals (n = 32) were evaluated for potential differences using surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF). Candidate markers were identified and validated using enzyme-linked immunosorbent assays (ELISA). Results: Several m/z values were expressed differentially between malignant and healthy control samples of the discovery set. Identification of the most prominent m/z value revealed C3a anaphylatoxin (C3a-desArg). ELISA based C3a-levels allowed correct classification of serum samples within the blinded validation set with 96 % sensitivity and specificity. Increased serum levels detected also 86 % of an independent sera (n = 36) set from patients with colorectal adenomas. Conclusions: Increased serum levels of C3a-desArg allowed correct group classification of patients with colorectal adenomas and carcinomas with high sensitivity and specificity (both 96 %, p < 0.0001). C3a-desArg serum level assessment could thus ameliorate existing screening tests for colorectal cancer.

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