Prognostic significance of the detection of peripheral blood CEACAM5mRNA-positive cells by real-time polymerase chain reaction in operable colorectal cancer

PURPOSE

To evaluate the clinical relevance of circulating CEACAM5mRNA-positive cells in patients with operable colorectal cancer (CRC).

METHODS

Peripheral blood was obtained from 265 patients with operable CRC before the initiation of adjuvant systemic therapy from 96 normal donors and RNA prepared from the Lovo and ARH-77 CRC and leukemic cell lines, respectively, was used as positive and negative controls. The detection of CEACAM5mRNA-positive cells was done using a real-time PCR assay. The association with known prognostic factors and the effect of CEACAM5mRNA-positive cells on patients' prognosis was investigated.

RESULTS

The analytical detection limit of the method was found to correspond to 0.7 Lovo cell equivalence/5 μg RNA, with a sensitivity of 1 tumor cell/10(5) normal cells and a specificity of 97%. Ninety-eight (37%) patients had detectable circulating CEACAM5mRNA-positive cells. Detection of CEACAM5mRNA-positive cells was significantly associated with higher relapse rate (P < 0.001), decreased disease-free survival (DFS; P < 0.001), higher death rate (P = 0.017), and decreased median overall survival (P = 0.025). Multivariate analysis revealed that the detection of circulating CEACAM5mRNA-positive cells was an independent prognostic factor for decreased DFS [HR = 3.4; 95% CI: 2.0-5.9; P < 0.001].

CONCLUSIONS

Detection of peripheral blood CEACAM5mRNA-positive cells is an adverse prognostic factor correlated with poor clinical outcome in patients with operable CRC.