Liquid biopsy biomarkers in breast cancer: An overview of systematic reviews

Breast cancer (BC) is the leading type of cancer affecting women globally and remains a significant cause of death. The diagnostic accuracy of liquid biopsy (LB) in the diagnosis of BC has not been well established. This overview synthesizes and critically evaluates the diagnostic test accuracy (DTA) of LB biomarkers in individuals with BC. Of 433 systematic reviews, eleven were included, assessing Fourier transform infrared (FTIR) spectroscopy, circulating tumor cells (CTCs), cell-free DNA (cfDNA), and microRNAs (miRNAs). The overall methodological quality of most of the reviews included was rated as critically low (n = 9, 81.8 %), and the remaining reviews were ranked as low and moderate. Key findings include CTCs with moderate sensitivity (0.50, 95 % confidence interval (CI) 0.48-0.52) and high specificity (0.93, 95 % CI: 0.92-0.95) with moderate certainty; cfDNA assays with high sensitivity (0.71-0.86) and specificity (0.88) with high certainty; FTIR assays with high sensitivity (0.97, 95 % CI: 0.94-0.96) and specificity (0.92, 95 % CI: 0.88-0.95) but low certainty. The miRNAs showed moderate to high sensitivity, while miR-21 had high specificity. Our overview indicates that identified liquid biopsies could serve as valuable tools for the diagnosis of breast cancer.