Objective: To test for circulating tumor cells (CTCs) relying on epithelial cellular adhesion molecule (EpCAM) expression in metastatic breast cancer by quantitative real-time reverse transcription-PCR.
Methods: In the study,47 metastatic breast cancer patients were evaluated by quantitative real-time PCR for detecting EpCAM mRNA. In addition, analyses were carried out for their correlation with patients' clinicopathologic features, response, and the time to progression (TTP).
Results: The sensitivity of EpCAM mRNA in the metastatic breast cancer patients was about 40%. However, the specificity of EpCAM mRNA for 20 healthy controls was 100%. TTP was calculated, and compared with that between EpCAM mRNA-positive and EpCAM mRNA-negative groups. For the retrospective study, the median TTP was 7.1 months and 11.1 months (P=0.013) for patients with EpCAM mRNA-positive and EpCAM mRNA-negative, respectively, after the first cycle chemotherapy. Moreover, a statistically significant correlation was demonstrated between EpCAM mRNA and TTP in patients who underwent the first or the second-line chemotherapy (P=0.018), but there was no significance in the patients pretreated with two or more previous chemotherapy lines (P=0.471).
Conclusion: This study provides evidence of the presence of EpCAM mRNA in approximately 40% of patients with metastatic breast cancer. There is a strong correlation between EpCAM mRNA results after the first cycle therapy and TTP in metastatic breast cancer patients, and EpCAM mRNA positive after chemotherapy may predict shorter TTP.