Non-blood body fluids as liquid biopsies in metastatic breast cancer

In this video, Camille Carette, a PhD student at the Laboratory for Translational Breast Cancer Research, presents research exploring the value of non-blood body fluids as an additional source for molecular profiling in patients with metastatic breast cancer, within the UPTIDER post-mortem tissue donation programme. 

Beyond blood, fluids such as pleural, peritoneal and pericardial effusions, as well as cerebrospinal fluid, can contain tumour cells and may offer complementary molecular information, often with a higher tumour cell content than blood. However, standardised collection protocols are still lacking, and receptor discordance between primary tumours and metastases is common, which can directly affect treatment decisions. 

The study evaluated whether tumour cells detected in these non-blood fluids are associated with metastases in nearby organ sites, and assessed the discordance of key clinical biomarkers (ER, PgR, HER2 and Ki67) across fluid and tissue samples. Tumour cells were found across all fluid types, most frequently in pleural fluid and ascites, but no significant association was observed between the presence of tumour cells in a specific fluid and metastases in nearby organ sites. 

Biomarker analyses showed that ER expression significantly correlated between fluid samples and solid metastases. In contrast, PgR, HER2 and Ki67 did not show significant correlation and intra-patient heterogeneity was observed. Overall, biomarker expression tended to be lower in the fluids compared with solid tumour samples.