Liquid Biopsy in Early Breast Cancer: A Preliminary Report

Background: Liquid biopsy (LB) is a technique that utilizes circulating biomarkers from cancer patients to provide information regarding the genetic landscape of the cancer. LB is emerging as an alternative and complementary diagnostic and prognostic tool to surgical biopsy and is expected to provide the tool for the implementation of precision oncology in clinical settings. In fact, it may contribute to enhance understanding of tumor heterogeneity and permitting the dynamic monitoring of treatment responses and genomic variations. Thus, LB is a promising method for the management of cancer, including breast cancer (BC), whose incidence in Italy is progressively increasing. Previous studies focused mainly on patients with advanced-stage BC. In the present study we evaluated the number of circulating tumor cells (CTCs), the quantity of cell free tumor DNA (cftDNA) and the analysis of the mutational profile of DNA from CTCs (ctcDNA) and cftDNA in early stage BC patients. Methods: Matched pre- and post-surgery blood samples were collected from 47 early stage BC patients. CTCs enumeration was done using Isoflux system, molecular profile of ctcDNA and cftDNA was performed with the Spotlight 59 Panels kit on a MiSeq Illumina instrument. Results: Eighty percent of samples was CTCs-positive, while healthy controls were all CTCs-negative. Forty-four patients provided a pre-surgery and 21 post-surgery sample. By comparing the number of CTCs post-surgery with that of pre-surgery, we found that 66% of patients showed a decreased number of CTCs, 14% of patients continued to have the same number of CTCs, while, interestingly, 19% of patients showed an increased number of CTCs. Next Generation Sequencing (NGS) of ctcDNA and cftDNA showed that 52% of samples had mutations in 9 genes (TP53, CDKN2A, FBXW7, PTPN11, KRAS, NRAS, BRAF, IDH1, ALK) and in 5 genes (PIK3CA, APC ALK, KRAS, TSC1), respectively, with KRAS and ALK overlapping and TP53 being the most frequently mutated gene in ctcDNA analysis. Conclusions: LB could facilitate early detection of minimal residual disease, aiding in the initiation of adjuvant therapy to prevent recurrence and progression towards metastasis, enhance individualized treatment and longitudinal screening, thus improving the clinical management and outcome of patients with early BC.