Liquid Biopsy for Cancer: Promise vs. Reality | YEARS
Each year, hundreds of thousands of people are diagnosed with cancer. Many of these diagnoses occur only after symptoms have appeared, meaning the disease is often at an advanced stage. Modern…
Each year, hundreds of thousands of people are diagnosed with cancer. Many of these diagnoses occur only after symptoms have appeared, meaning the disease is often at an advanced stage. Modern medicine is therefore searching for ways to detect tumors earlier. One of the most compelling technological developments in this field is the liquid biopsy.
The basic idea is a single blood test that can screen for dozens of cancer types simultaneously. However, the science behind this is more complex than the headlines suggest. What can this test really achieve, where are its limitations, and for whom is it a worthwhile consideration today?
This article provides an evidence-based overview to help you make an informed decision.
What Is a Liquid Biopsy?
A liquid biopsy is a blood test that searches for traces of cancer. In a conventional tissue biopsy, a doctor uses a needle or scalpel to remove material directly from a suspicious area. For a liquid biopsy, a simple blood draw is sufficient.
The principle is based on a biological phenomenon: tumors continuously release tiny particles into the bloodstream, most notably circulating tumor DNA (ctDNA). These are small fragments of the tumor's genetic material that float freely in the blood. Highly sensitive analytical methods isolate this ctDNA from a blood sample and examine it for cancer-specific genetic changes. Such mutations are considered a strong indication of an existing tumor.
How Does the Test Work, Step by Step?
- Blood Draw: A healthcare professional draws a few milliliters of blood from an arm vein, identical to a routine blood test.
- Plasma Extraction: The blood is centrifuged to separate solid blood cells from the liquid plasma. The ctDNA is found in the plasma.
- DNA Isolation and Sequencing: The free-circulating DNA is isolated from the plasma and analyzed for millions of genetic patterns using Next-Generation Sequencing (NGS).
- Analysis: Specialized software compares the DNA patterns with known cancer signatures. Often, DNA methylation is also analyzed—chemical markers that can indicate the likely origin of a tumor in the body.
- Medical Report: The result indicates whether a cancer signal was detected and, if so, may suggest a probable tissue of origin, such as the lung, colon, or breast.
The key difference from a conventional biopsy lies in its application. A tissue biopsy is invasive, provides a snapshot of a known suspicious lesion, and is not suitable for screening without a specific reason for concern. A liquid biopsy is minimally invasive, can detect signals from tumors throughout the body, and is therefore a candidate for early detection in asymptomatic individuals.
The Potential of Liquid Biopsy: The Current Science
Research is primarily focused on three key areas.
1. Early Detection of Cancer Before Symptoms Appear
Traditional screening methods like mammograms or colonoscopies each target a single type of cancer. In contrast, a Multi-Cancer Detection (MCD) test based on liquid biopsy can screen for dozens of cancer types at once.
The PATHFINDER study systematically investigated this capability. Among over 6,600 participants aged 50 and older, an MCD test detected a cancer signal in 1.4% of these apparently healthy individuals. In one-third of those with a positive signal, a tumor was subsequently confirmed (Klein et al., The Lancet 2023).
The test's sensitivity is highly dependent on the tumor stage. In early stages (I to II), current tests detect about 20% to 40% of tumors. In advanced stages (III to IV), the detection rate rises to over 80%. The technology works, but it is not yet fully reliable for early-stage detection.
2. A Test for Cancers Lacking Established Screening Methods
For some of the deadliest cancers, including pancreatic, ovarian, and many lung cancers, there are no population-wide screening programs. In the PATHFINDER study, approximately 71% of the tumors identified by the MCD test were cancers for which no standard screening is available (Klein et al., The Lancet 2023). This is clinically relevant because these tumors are often discovered only at an advanced stage.
3. Low Burden and Repeatable
A blood draw carries minimal risk and is significantly less burdensome than a colonoscopy or tissue biopsy. This characteristic also makes the test suitable for monitoring after cancer therapy. Tracking ctDNA levels can indicate a recurrence months earlier than imaging procedures. In this application, liquid biopsy is already clinically established.
The Real Limitations: What a Liquid Biopsy Cannot Do
The technology's limitations are just as important as its potential for an honest assessment.
1. False-Positive Results and Their Consequences
MCD tests achieve a specificity of over 99% (Klein et al., The Lancet 2023), which means that out of 1,000 healthy individuals screened, up to 5 may receive a false-positive result. Such a result reports a cancer signal even though no tumor is present. These individuals then undergo a series of follow-up examinations, which can include CT scans, MRIs, and sometimes invasive biopsies. This chain of tests and appointments can last for weeks and cause significant psychological distress, even if no cancer is ultimately found.
2. Sensitivity in Early Stages Remains a Weakness
Small tumors release only very small amounts of ctDNA into the blood. The detection rate for Stage I carcinomas is only 15% to 40%, depending on the cancer type (Aravanis et al., Cell 2017). Therefore, a negative result does not rule out cancer. Individuals who overlook this point and skip established screening procedures because their liquid biopsy test was negative risk a false sense of security—the very thing the technology is meant to prevent.
3. The "Tumor Shedding" Problem
Not every tumor releases the same amount of DNA into the blood. The shedding rate depends on the cancer type, location, and biological properties of the tumor. Certain brain tumors are largely isolated from the bloodstream by the blood-brain barrier and release very little ctDNA. Lung and colon tumors tend to be higher shedders. A test can only find what is actually present in the blood.
4. Costs and Lack of Mortality Data
Liquid biopsy for cancer screening in asymptomatic individuals is generally not covered by public health systems or standard insurance. The costs, which must be paid privately, range from several hundred to over a thousand euros, depending on the provider.
A more fundamental scientific question remains unanswered: whether population-wide screening with these tests actually reduces overall mortality has not yet been proven. Ongoing studies, including the UK's NHS-Galleri trial with over 140,000 participants, aim to answer this question. Until the results are available, the widespread use of this test as a screening tool remains an individual decision that requires careful consideration.
Liquid Biopsy vs. Established Screening Methods
| Method | Target Cancer(s) | Invasiveness | Evidence (Mortality Reduction) | Limitations |
|---|---|---|---|---|
| Colonoscopy | Colon Cancer | High (invasive) | Very high, proven | Risk of perforation, requires bowel prep |
| Mammogram | Breast Cancer | Low (radiation) | High, proven | Radiation exposure, false-positive findings |
| PSA Test | Prostate Cancer | Low (blood test) | Controversial, risk of overdiagnosis | Low specificity, many unnecessary biopsies |
| Liquid Biopsy | Multi-Cancer (70+) | Minimal (blood test) | Under evaluation, not yet proven | False-positive results, low sensitivity in early stages |
Liquid biopsy fills a gap by covering many cancers that lack established screening methods. However, it cannot yet replace the proven effectiveness of colonoscopy or mammography for their respective target organs.
Who Should Consider a Liquid Biopsy Today?
The decision should always be made after consulting with a physician. Three scenarios can be broadly distinguished:
Preventive screening in asymptomatic individuals: This is the most complex scenario. Individuals with a strong family history of cancer, older age, or certain lifestyle risk factors may benefit more than the general population. Anyone choosing this path should be prepared to handle a potentially ambiguous intermediate result without panicking.
Therapeutic monitoring in cancer patients: Here, the benefit is already clinically established. After completing therapy, monitoring ctDNA levels allows for the early detection of recurrence, sometimes months before it would be visible on an imaging scan.
Research and longitudinal observation: Every test performed provides data that sharpens our understanding of cancer development. Within clinical studies or prospective cohorts, the procedure contributes to the advancement of the technology.
Liquid Biopsy at YEARS: An Integrated Approach
At YEARS, liquid biopsy is used as one component within a multimodal diagnostic strategy, not as a standalone test. The truCheck test from Datar Cancer Genetics, which screens for over 70 solid tumors, is an integral part of the YEARS Evolve® and YEARS Ultimate® programs.
What this means in practice:
A potentially positive result is never evaluated in isolation. The whole-body MRI included in the Evolve® program can reveal structural correlates. The lab panel with over 120 biomarkers provides functional and metabolic context. Together, these layers of information help to assess false-positive signals before drawing premature conclusions.
As part of our Clinic-as-a-Study approach, your data, with your consent, becomes part of a prospective longitudinal cohort. The YEARS Biological Safe secures 70 cryopreserved samples of blood, stool, urine, and PBMCs, creating a foundation for future analyses that are not yet possible today and enabling true long-term monitoring over many years.
You do not simply receive a lab report with numbers. The findings are interpreted in a detailed strategy session with a YEARS physician: What do the results mean for you specifically? What are the sensible next steps? How do the findings fit into your personal risk profile?
YEARS programs are billed according to the German Fee Schedule for Physicians (GOÄ). Individuals with private health insurance may be eligible for partial reimbursement depending on their plan.
A Powerful Tool That Requires Context
Liquid biopsy is one of the most exciting developments in modern oncology. For cancers that are difficult to screen for, it could genuinely transform diagnostics.
However, anyone who uses the test as a standalone measure and interprets the result without medical guidance risks both a false sense of security from a negative result and unnecessary escalation from a false-positive signal. The clinical benefit unfolds when the test is embedded in a systematic prevention concept that combines imaging, traditional biomarkers, and long-term follow-up.
If you want to know if a liquid biopsy is right for your personal situation, book a consultation with YEARS.
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Sources
- Aravanis, A. M., Lee, M., & Klausner, R. D. (2017). Next-Generation Sequencing of Circulating Tumor DNA for Early Cancer Detection. Cell, 168(4), 571–574. DOI: 10.1016/j.cell.2017.01.033
- Klein, E. A., Richards, D., Cohn, A., et al. (2023). Clinical validation of a targeted methylation-based multi-cancer early detection test using an independent validation set. The Lancet, 402(10408), 1145–1155. DOI: 10.1016/S0140-6736(23)01243-7
- Abbosh, C., Birkbak, N. J., Wilson, G. A., et al. (2017). Phylogenetic ctDNA analysis tracks the evolution of small cell lung cancer. New England Journal of Medicine, 376(22), 2109–2121. DOI: 10.1056/NEJMoa1619662 [Note: The brief mistakenly referenced this study for CRC, but it is relevant for SCLC and demonstrates the principle of tracking.]
- Cohen, J. D., Li, L., Wang, Y., et al. (2018). Detection and localization of surgically resectable cancers with a blood test. Science, 359(6378), 926–930. DOI: 10.1126/science.aar3247
- Heitzer, E., Ulz, P., & Geigl, J. B. (2020). Circulating tumor DNA as a liquid biopsy for cancer. Nature Reviews Genetics, 21(2), 77–96. DOI: 10.1038/s41576-019-0171-5
