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Get Acquainted with Liquid Biopsies

Welcome to the exciting world of liquid biopsies! This is a relatively new diagnostic method which revolutionises how we approach cancer and infectious disease diagnoses. In this series, we'll be diving into the science behind liquid biopsies, exploring their potential applications, and getting a glimpse into the future of this cutting-edge testing method.

What is a Liquid Biopsy?

Let's start by comparing liquid biopsies to traditional biopsies. Traditional biopsy procedures are often invasive and have accompanying risks such as pain, bleeding, infection, and scarring. They also require significant preparation time, making them stressful and inconvenient for patients. Liquid biopsies, on the other hand, offer a non-invasive and simple solution. Instead of tissue removal, a liquid biopsy only requires a patient to provide a blood sample, which researchers then analyse for molecular disease markers. This innovative process represents a significant step in diagnostics and opens up exciting new possibilities in personalised medicine.

Liquid Biopsies and Cancer

Studies dating to the early 2000s showed that cancer cells could circulate in the bloodstream, and researchers could use them as diagnostic biomarkers. This discovery sparked interest in liquid biopsy, later defined as the analysis of circulating tumour cells (CTCs) and circulating tumour DNA (ctDNA) in the bloodstream. Researchers soon found that CTCs and ctDNA were prognostic biomarkers in various solid tumours, including metastatic breast, prostate, lung, and colorectal cancer. Today, researchers are conducting hundreds of clinical trials on these liquid biomarkers.

DEFINITION BOX: Metastasis is the process of spreading cancer cells from the primary tumour to other body parts through the bloodstream or lymphatic system. The method of disseminating cancer cells into the bloodstream involves the cancer cells breaking away from the primary tumour and entering the bloodstream. This process means they can travel to other body parts and establish secondary tumours. Metastasis is an essential factor in cancer progression, as it allows cancer to grow and spread beyond the initial site of the primary tumours.

Enter: The Liquid Biopsy

The term "liquid biopsy" was coined in 2010 by Catherine Alix-Panabières and Klaus Pantel. This term comprehensively describes the analysis of CTCs in the bloodstream. However, experts soon expanded the concept to include another circulating biomarker – circulating tumour DNA (ctDNA).

Research into liquid biopsy expanded rapidly, and experts highlighted CTCs and ctDNA as prognostic biomarkers in solid tumours such as breast, prostate, lung, and colorectal cancer. Further, hundreds of clinical trials are currently pursuing these liquid biomarkers.

A Liquid Biopsy Bonus

One of the best things about liquid biopsies is that they can provide information on multiple biomarkers from just one blood sample. In addition, centrifugation enables the separation of the blood into plasma and cellular fractions, allowing researchers to analyse complementary circulating biomarkers such as extracellular vesicles, proteins, cell-free RNA, tumour-educated platelets, CTCs, and tumour-infiltrating lymphocytes.

Expanding Horizons

Liquid biopsy is not limited to just blood extraction. Samples of other bodily fluids, such as saliva, urine, cerebrospinal fluid, and bone marrow, can also provide valuable diagnostic information. For example, analysing cerebrospinal fluid can give insights into brain tumours, while saliva and sputum can help diagnose head, neck, and lung cancers. In addition, urine samples can help diagnose bladder, kidney, and prostate cancers, and bone marrow biopsies can detect markers for breast, prostate, lung, and colorectal cancers.

The future of liquid biopsy looks bright, with the discovery of alternative circulating biomarkers and the development of new technologies. This minimally invasive testing method offers a promising alternative to traditional biopsy procedures and holds great potential for diagnosing cancer and other diseases. In the next instalment of our series, we'll dive into the practical applications of liquid biopsies and what this means for patients and healthcare professionals.

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