Concordance Between Liquid and Tissue Biopsy

In Canada, it is estimated that more than 26,900 women will be diagnosed with breast cancer (BC), and 5,000 women will die from BC in 2019. Metastatic BC will cause the vast majority of these deaths. Tissue biopsy is recommended to confirm recurrence (presence of cancer cells) in patients with a history of previous BC. Additionally, tissue biopsy provides information on BC subtypes (estrogen receptor (ER), progesterone receptor (PgR), and HER2 status). Technological advances over the last several years have led to more robust methods for the detection, quantification, and characterization of liquid biopsy (including CTCs and ctDNA) in recurrent BC. If these approaches demonstrate sufficiently concordant results to tissue-based testing, blood draws may quickly become a viable alternative to invasive biopsies. In a cross-sectional study, 120 consecutive individuals from study centers in Ontario, who present with highly suspicious BC distant metastases who undergo biopsy to confirm BC recurrence will be enrolled (enrollment will be continued until 100 subjects with confirmed metastatic breast cancer have been enrolled). Blood samples for the circulating factors will be taken within 30 days prior to the tissue biopsy. Patient and tumor characteristics will be recorded. At the end of study, liquid biopsy (CTCs and ctDNA) analyses will be performed blinded to biopsy results. Investigators will continuously review the number of participants in each BC subtype. Cases with tissue biopsy results not classified as definite or highly suspicious for metastatic breast cancer by the treating physician will be re-assessed after six month of study entry in an attempt to classify them as having metastatic breast cancer or not. This aims to confirm/rule out breast cancer or other diagnosis. The overall anticipated public and/or scientific benefit of the study is to demonstrate the concordance between liquid (blood) biopsy and tissue based tests in terms of the presence of cancer cells, hormone receptors, HER2 status etc. so these tests could be used in the future to confirm diagnosis using a non-invasive procedure. The results of this study will advance our understanding of liquid biomarkers and ideally improve the care journey for breast cancer patients by not subjecting them to invasive and potentially dangerous biopsy procedures.