CD133 Expression in Circulating Tumor Cells as a Prognostic Marker in Colorectal Cancer

Identifying prognostic markers in colorectal cancer (CRC) is crucial for improving treatment outcomes. Although carcinoembryonic antigen (CEA) is recommended in the guidelines of the National Comprehensive Cancer Network, its sensitivity and specificity are inconsistent, limiting its utility in patients with normal CEA levels. Circulating tumor cells (CTCs), including those expressing CD133—a cancer stem cell marker involved in tumor progression and therapy resistance—are associated with metastasis and survival outcomes. This study evaluated the prognostic significance of CD133-positive CTCs, and their combined effect with CEA, in patients with CRC. Peripheral blood samples from 195 patients with CRC (stages I–IV) were analyzed. CTCs were isolated using OncoQuick tubes and CD133 mRNA expression was detected by reverse transcription polymerase chain reaction. In clinicopathological analysis, CD133-positive CTCs were detected in 27.2% of cases, correlating with serosal invasion (P=0.016). Multivariate Cox analysis showed that CD133-positive CTCs were associated with worse disease-specific survival (P=0.001). Patients with CD133-positive CTCs and CEA ≥5 ng/mL (high CEA) had a significantly poorer prognosis (P<0.001), whereas those with CD133-negative CTCs and CEA <5 ng/mL (low CEA) had a better prognosis (P=0.039). CD133 expression in CTCs, especially in combination with CEA, may serve as a valuable prognostic marker in CRC.