science

Liquid biopsy

Liquid biopsy is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Liquid biopsy rather than just read about it. In short: A liquid biopsy, also known as fluid biopsy or fluid phase biopsy, is the sampling and analysis of non-solid biological tissue, primarily blood. Like traditional biopsy, this type of technique is mainly used as a diagnostic and monitoring tool for diseases such as cancer, with the added benefit of being largely non-invasive.

Key takeaways

Liquid biopsy belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Liquid biopsy to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Liquid biopsy from memory before moving on to harder problems.

Reference excerpt

A liquid biopsy, also known as fluid biopsy or fluid phase biopsy, is the sampling and analysis of non-solid biological tissue, primarily blood. Like traditional biopsy, this type of technique is mainly used as a diagnostic and monitoring tool for diseases such as cancer, with the added benefit of being largely non-invasive. Liquid biopsies may also be used to validate the efficiency of a cancer treatment drug by taking multiple samples in the span of a few weeks. The technology may also prove beneficial for patients after treatment to monitor relapse. The clinical implementation of liquid biopsies is not yet widespread but is becoming standard of care in some areas. Liquid biopsy refers to the molecular analysis in biological fluids of nucleic acids, subcellular structures, especially exosomes, and, in the context of cancer, circulating tumor cells.

Types There are several types of liquid biopsy methods; method selection depends on the condition that is being studied.

A wide variety of biomarkers may be studied to detect or monitor other diseases. For example, isolation of protoporphyrin IX from blood samples can be used as a diagnostic tool for atherosclerosis. Cancer biomarkers in the blood include PSA (prostate cancer), CA19-9 (pancreatic cancer) and CA-125 (ovarian cancer).

Mechanism

Circulating tumor DNA (ctDNA) refers to DNA released by cancerous cells into the blood stream. Cancer mutations in ctDNA mirror those found in traditional tumor biopsies, which allows them to be used as molecular biomarkers to track the disease. These tests can have sensitive limits of detection, allowing monitoring of minimal residual disease after treatment. Scientists can purify and analyze ctDNA using next-generation sequencing (NGS) or PCR-based methods such as digital PCR. NGS-based methods provide a comprehensive view of a cancer's genetic makeup and is especially useful in diagnosis while digital PCR offers a more targeted approach especially well-suited for detecting minimal residual disease and for monitoring treatment response and disease progression. Recent progress in epigenetics has expanded the use of liquid biopsy for the detection of early-stage cancers, including by approaches such as Cancer Likelihood in Plasma (CLiP) . Liquid biopsies can detect changes in tumor burden months or years before conventional imaging tests can, making them suitable for early tumor detection, monitoring, and detection of resistance mutations. The increase in the adoption of NGS in various research fields, advancement in NGS, and increase in the adoption of personalized medicine are expected to drive growth in the global liquid biopsy market.

Clinical application In cancer, liquid biopsy can be used for either multi-cancer screening tests, when solid tumor biopsies are not possible, to compare different treatments as part of clinical trials, to inform decisions for doctors/patients on which precision medicine treatment to select, and for minimal residual disease detection (disease monitoring). Liquid biopsy of circulating tumor DNA for EGFR-mutated lung cancer is approved by the FDA. The CellSearch method for enumeration of circulating tumor cells in metastatic breast, metastatic colon, and metastatic prostate cancer has been validated and approved by the FDA as a useful prognostic method.

See also Radiographic imaging Cancer screening#Blood tests Circulating free DNA

External links NucPosDB: a database of nucleosome positioning in vivo and nucleosomics of cell-free DNA

References

Worked examples

Example 1 — a first encounter with Liquid biopsy

Start with the simplest possible case. Write down what Liquid biopsy claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Liquid biopsy before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Liquid biopsy ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Liquid biopsy

In research: Liquid biopsy appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Liquid biopsy in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Liquid biopsy is common in secondary-school and first-year university syllabi. It links to neighbouring topics Biopsy, Blood tests, Cancer diagnostics, so understanding it makes those chapters shorter.
In everyday life: Look for Liquid biopsy outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Liquid biopsy in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Liquid biopsy means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Liquid biopsy out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Liquid biopsy in simple terms?

Why does Liquid biopsy matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Liquid biopsy?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Liquid biopsy.