While traditional cancer screenings remain the gold standard, a promising new technique – liquid biopsy – is fast becoming a game-changer in early detection. How does it compare to existing methods, and could it revolutionise cancer screening?
Hearing the word “cancer” can be life-changing. For many, a diagnosis comes with shock, fear, and regret – especially when routine screenings were overlooked despite known risks.
Cancer remains as one of the leading causes of morbidity and mortality worldwide. Early detection through screening plays a crucial role in reducing cancer-related deaths by identifying malignancies at a treatable stage.
In an interview with Medical Channel Asia, Dr Steven Tucker, Medical Oncologist at Tucker Medical, emphasised the importance of early cancer detection through screening. He also shared that the goal for cancer screening is to find it early while it is smaller and more curable with lesser harm during treatment.
Cancer screening usually includes tumour marker tests and traditional cancer-screening methods. A relatively new technique called liquid biopsy has emerged as a promising method in cancer screening.
Here, let’s explore the different types of cancer screening, including liquid biopsy.
What are Tumour Marker Tests?
Tumour markers are substances produced by cancer cells or by the body in response to cancer. These substances can be detected in blood, urine or tissue samples.
Tumour marker tests are often used in cancer screening, diagnosis, and monitoring treatment response. They are most effective when used alongside imaging and clinical assessments rather than as standalone screening tools.
Some tumour markers are specific to certain cancers. For example:
Tumour Markers | Cancer |
Cancer Antigen 15-3 (CA 15-3) | Breast cancer |
Cancer Antigen 19-9 (CA 19-9) | Pancreatic cancer |
Cancer Antigen 125 (CA-125) | Ovarian cancer |
Carcinoembryonic Antigen (CEA) | Colorectal cancer |
Prostate-Specific Antigen (PSA) | Prostate cancer |
Alpha-Fetoprotein (AFP) | Hepatocellular carcinoma (a type of liver cancer) |
While tumour marker tests offer a non-invasive way to detect cancer, their accuracy may be limited due to:
- Low specificity
Elevated tumour marker levels can occur in benign conditions, leading to false positives.
- Low sensitivity
Some cancers do not produce detectable tumour markers in the early stages, and may not be picked up by these tests, leading to false negatives.
- Variability
Different individuals may have varying baseline levels. This may affect the test results interpretation.
Traditional Cancer Screening Methods

Several established screening tests are widely used for different types of cancer. While some may be invasive, these cancer screening tests are more accurate than tumour markers.
Breast Cancer
- Mammography is the gold-standard imaging tool for breast cancer screening.
- Breast ultrasound and MRI are supplementary imaging tools for high-risk individuals.
Cervical Cancer
- Pap smears and HPV tests detect precancerous cells before cervical cancer develops.
Lung Cancer
- Low-dose CT (LDCT) is an imaging scan to screen for lung cancer in high-risk individuals, such as heavy smokers.
Prostate Cancer
- A digital rectal examination (DRE) checks for lumps and is used alongside with Prostate-Specific Antigen (PSA) tumour marker test in prostate cancer screening.
- Multiparametric MRI (mpMRI) is an advanced imaging technique to screen for prostate cancer.
What’s New Here – Liquid Biopsy

Liquid biopsy is a blood test that detects cancerous tumours circulating in the bloodstream. It analyses blood samples to detect tumour-derived genetic material such as circulating tumour DNA (ctDNA) and circulating tumour cells (CTCs).
ctDNAs are DNA fragments shed by tumour cells into the bloodstream. Meanwhile, CTCs are intact cancer cells from tumours that travel through the bloodstream.
Benefits of Liquid Biopsy
Liquid biopsy may offer multiple advantages in cancer screening, such as:
- A minimally invasive technique
Unlike traditional biopsies that need tissue extraction, liquid biopsy only requires a blood draw which is more convenient and less painful.
- Rapid test results
Liquid biopsy can produce results quickly such as within 10 days. Traditional tissue biopsy may take longer.
- Potential early cancer detection
Liquid biopsy is very sensitive at identifying minute traces of ctDNA. This allows cancer detection at an earlier stage before it becomes symptomatic or life-threatening.
- Real-time monitoring
Liquid biopsy allows continuous monitoring of tumour progression and treatment response with ctDNA levels.
- Detection of multiple cancers
Liquid biopsy can test for multiple cancers simultaneously.
Challenges with Liquid Biopsy
While liquid biopsies may offer various potential benefits, it is still essential to acknowledge their limitations.
- Liquid biopsies might not detect some small tumours or cancers in early stages as effectively as traditional biopsies. Hence, it should not be a substitute to the standard cancer-screening methods.
- Depending on the cancer type and stage, the sensitivity and specificity of liquid biopsy tests can vary.
- The levels of ctDNA in the blood can also fluctuate, affecting the accuracy of the liquid biopsy results. Inaccuracies can lead to unnecessary anxiety or missed diagnosis.
- Liquid biopsy can be costly compared to traditional cancer-screening procedures.
Summary
Advantages of Liquid Biopsy
- Minimally invasive blood draw replaces the need for surgical tissue extraction
- Faster results within 10 days, compared to longer wait times for traditional biopsies
- Potential for early detection – Highly sensitive to tiny traces of ctDNA, allowing earlier cancer identification
- Real-time monitoring – Helps track tumour progression and treatment response
- Multi-cancer screening – Has the potential to detect different types of cancer in one test
Limitations of Liquid Biopsy
- May miss small or early-stage tumours
- Variable accuracy – Sensitivity and specificity differ depending on cancer type and stage
- Fluctuating ctDNA levels may lead to false positives or missed diagnoses
- High cost – More expensive than conventional screening methods
What is the Future Direction?
Liquid biopsy may represent a significant breakthrough in cancer screening. Both liquid biopsies and traditional established methods are able to detect cancer in their own ways. While the benefits may seem promising, liquid biopsy should be used in complement the standard cancer-screening methods.
More research is needed to further enhance the test sensitivity and specificity. As research continues, improvements in accuracy and cost-effectiveness could make liquid biopsy a powerful mainstream cancer screening method in the future.
Regular cancer screenings save lives. Whether through tumour marker tests, imaging scans, or emerging technologies like liquid biopsy, early detection remains our best defense against cancer. If you are at risk or overdue for a screening, consider speaking to a healthcare professional today.
Curious about liquid biopsy, cancer screening, and how it affects you?
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