Receptor discordance between primary tumor and metastasis influences CTC-status

Circulating tumor cell (CTC) detection is a prognostic factor in the metastatic breast cancer (MBC) setting. Discrepancies in primary (PT) and metastatic tumor (MT) genetic profiles are also of prognostic importance. Our study aimed to compare the CTC statuses and prognoses between those with subtype stable MBCs and MBCs with specific biomarker conversions.

The study enrolled 261 MBC patients treated at the National Center for Tumor Diseases, Heidelberg, Germany in a five-year period. All underwent PT and MT biopsies and subsequent CTC enumeration before the initiation of systemic therapy. ER and HER2 statuses of the PTs and MTs were determined and progression free survivals (PFSs) and overall survivals (OSs) were recorded. We compared CTC statuses, CTC counts, PFSs and OSs between patients with different receptor change patterns. Subgroups differences were analyzed utilizing Wilcoxon rank sum and Chi-squared tests, while Kaplan-Meier plots and log-rank tests were used to compare PFSs and OSs.

CTC counts were similar in all groups. Patients with a stable HER2 expression were less likely to be CTC positive, while the converse is true of patients acquiring HER2 and ER and those with triple negative tumors. Patients who had tumors that converted to triple negative MTs had the shortest median OSs while HER2 expression was not associated with a shorter median OS. No significant differences in PFSs and OSs have been demonstrated by Kaplan-Meier curve comparisons.

CTCs may provide a useful surrogate marker for aggressive metastatic cancer, offering a possibility of liquid biopsy-based therapy monitoring.

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Publication History

Article published online:
07 October 2020