KRT19 and CEACAM5 mRNA-marked circulated tumor cells indicate unfavorable prognosis of breast cancer patients.

Aim: To investigate the clinical and prognostic significance of circulated tumor cells (CTC) marked by cytokeratin 19 coding gene KRT19 mRNA and carcinoembryonic antigen coding gene CEACAM5 mRNA in preoperative peripheral blood of breast cancer patients and provide molecular markers for breast cancer metastasis risk.
Methods: The mRNA levels of KRT19 and CEACAM5 in preoperative peripheral blood of breast cancer patients without (n = 603) and with (n = 76) distant metastases at the time of initial diagnosis were detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The relationship between CTC _KRT19 , CTC _CEACAM5 and clinicopathological features, local recurrence-free survival (LRFS), distant metastasis-free survival (DMFS), or overall survival (OS) was statistically analyzed.
Results: In different pathological stages of breast cancer, the rates of CTC _KRT19-pos and CTC _CEACAM5-pos increased with the increase of the stages (P = 0.077 and P = 0.004). Preoperative CTC _KRT19-pos in breast cancer patients was closely related to the lymph node metastasis statues (P < 0.0001), and had no significant correlation with other clinicopathological features. There was no significant correlation between CTC _CEACAM5 and the clinicopathological features. Patients with high levels of CTC double-marked by KRT19 and CEACAM5 mRNA had shorter DMFS (P < 0.0001) and OS (P = 0.016) for patients with breast cancer. The 7-year DMFS rates for the low-, intermediate-, and high-risk groups were 90.7%, 67.5%, and 59.1%, respectively (P < 0.0001). The prognosis of patients with decreased KRT19 and CEACAM5 mRNA after treatment is better than that of patients who have not decreased, and the combination of the two indicators is better than the single one for predicting PFS (P = 0.002 compare with P = 0.036 or P = 0.047).
Conclusion: Double-marked CTC by KRT19 and CEACAM5 mRNA is a prognostic index of breast cancer patients before surgery and after chemotherapy. Single-marked CTC by KRT19 mRNA indicates lymph node statues of preoperative patients. Therefore, the RT-qPCR-based molecular diagnosis of CTC could be used for prognostic prediction of breast cancer patients and guiding clinical treatment.