Concordance of HER2 status between primary tumor and circulating tumor cells in breast cancer

During tumor progression, HER2 expression undergoes dynamic changes. Circulating tumor cells (CTCs) can be used to monitor HER2 expression in real-time and hold potential for clinical application. This study aimed to evaluate the consistency of HER2 expression between primary tumors and CTCs in patients with breast cancer (BC).

We used a previously established telomerase reverse transcriptase-based CTC detection method (TBCD) combined with anti-HER2 antibody to detect CTC and HER2-positive CTC (HER2 + CTC) in 4 ml of peripheral blood from patients with breast cancer prior to radiotherapy. The results indicated that the status of HER2 in CTC was inconsistent with the histological results.

Discordance in HER2 status between primary tumor and CTC was observed in 32.6% of patients (kappa value = 0.325, p = 0.03). And among patients with histologically HER2-negative breast cancer, the detection rate of HER2 + CTC was 32.1% (9/28).

We found that the HER2 status of CTC in peripheral blood was inconsistent with the histological findings. Further research should explore the clinical significance of detecting HER2-positive CTCs, and it is desired that real-time HER2 status testing of CTCs could hold potential value for patients with breast cancer.