Preface

**Section 4 Other Targets of Liquid Biopsy 99**

**Biopsies 101** Byron Baron

**VI** Contents

Chapter 7 **The Diagnostic and Prognostic Application of Heat Shock**

Chapter 8 **Blood-Brain Barrier Breakdown by Combined Detection of**

Natalia Malara and Giuseppe Donato

**Proteins and their Post-Translational Modifications from Liquid**

**Circulating Tumor and Endothelial Cells in Liquid Biopsy 127**

Reliable diagnosis is the cornerstone, starting point, and prerequisite of successful treat‐ ment. Therefore, research devoted to innovative diagnostic technologies continues to ad‐ vance at a rapid pace. The field of liquid biopsy is a bright example of such progress.

Liquid biopsy is a new minimally invasive laboratory evaluation concept that can be used for diagnostic, prognostic, and predictive testing, as well as dynamic monitoring of treat‐ ment efficacy or disease course. To achieve these goals, a multitude of specific, targeted tests can be performed to detect free nucleic acids, exosomes, microRNAs, tumor-educated plate‐ lets, and whole cells of tumor or fetal origin in different biological fluids, including blood, urine, cerebrospinal fluid, and others.

Although tissue biopsy has long been considered the gold standard of diagnostics, especial‐ ly regarding malignant tumors, liquid biopsy has the advantages of a non-invasive ap‐ proach and thus low risk of complications. It is technically feasible even in serious general status or if tumors or metastases are not easily accessible using conventional tissue biopsy. The testing is fast, exact, and can be repeated to ensure real-time follow-up during treatment or surveillance. In contrast to classic tumor markers, e.g., prostate-specific antigen, liquid biopsy is distinguished by high specificity at genomic, proteomic, and cellular levels. It is expected to equal and exceed the diagnostic value of tissue biopsy. The field of liquid biop‐ sies is developing rapidly regarding the selection of targets, technological improvements, and quality assessment. Further research is clearly needed, and a summary of the existing knowledge in this book will support it.

The chapters in this book provide state-of-the-art reviews on the current knowledge and ad‐ vances in the technologies, software, and diagnosis-based research regarding the field of liq‐ uid biopsy. This book is written by a global team of recognized medical experts and researchers. We would like to thank all the authors for their excellence, cooperation, and work input.

We are particularly grateful to Lucija Tomicic-Dromgool, Marina Dusevic, and their collea‐ gues at IntechOpen, one of the world's leading multidisciplinary scientific publishers of open access books. The IntechOpen team was remarkable for their expertise and continuous, kind support in bringing this edition to completion.

Finally, we would like to thank our colleagues and students in Riga Stradins University for the inspiring atmosphere and genuine love of science in general and medical research in particular. The future starts with the bright eyes of students and relevant questions. We hope that the book will provide answers to some of those questions and inspiration for fur‐ ther study, culminating in future research, technologies, and practical implementation of liq‐ uid biopsy in clinical medicine.

> **Ilze Strumfa and Janis Gardovskis** Riga Stradins University, Latvia

**Section 1**

**Introduction**

**Section 1**
