Next-generation sequencing-based liquid biopsy offers a promising approach to detecting breast cancer through blood samples, though it cannot yet replace traditional mammography for early-stage screening.

Next-generation sequencing-based liquid biopsy offers a promising approach to detecting breast cancer through blood samples, though it cannot yet replace traditional mammography for early-stage screening.

Next-generation sequencing-based liquid biopsy offers a promising approach to detecting breast cancer through blood samples, though it cannot yet replace traditional mammography for early-stage screening.

Breast cancer is one of the most common cancers experienced by women, and early detection improves the effectiveness of treatment. Given the rise in interest in preventive health care, an increasing number of people inquire whether a simple blood test might be able to detect breast cancer even in the absence of symptoms. The answer has been evolving due to next-generation sequencing-based liquid biopsy, one of the breaking discoveries in the area of cancer detection.

Why conventional blood tests fall short

It is not advisable to use routine blood tests for breast cancer screening. Elevated tumour markers like CA15-3 and carcinoembryonic antigen (CEA) may be due to benign diseases and can be normal in early stages of the disease. Their use is limited to monitoring patients who are undergoing treatment for breast cancer. Hence, it is inappropriate to use tumour markers to screen healthy individuals. A normal result of tumour markers does not exclude breast cancer.

What is NGS-based liquid biopsy?

Tumours release small parts of their DNA into the blood. These bits of DNA mix with the abundance of cell-free DNA sent out by healthy cells. Liquid biopsy tests blood samples for the presence of these bits, while NGS enables one to scan millions of DNA pieces simultaneously, which allows one to identify very weak cancer signals. NGS tests can detect three different signals:

  • Genetic mutations in tumour cells
  • DNA methylation markers, which differ between healthy and diseased cells and indicate the site of origin of the tumour.
  • Fragmentation patterns, or characteristics of cell-free DNA fragments.

Through a combination of these signals, including the use of machine learning, it is possible to detect tumours with higher precision. Multiple cancer early diagnosis tests take advantage of this technology to search for several types of cancer with a single blood sample.

Where it stands for early breast cancer

There is fast progress in the field of NGS-based liquid biopsy techniques, but it is still a problem to use them for detecting early breast cancer. There is not enough ctDNA secreted by small and local tumours, which is why the existing tests cannot detect early breast cancer as frequently as they detect advanced or aggressive forms of this disease. It is reported that there are ongoing clinical trials that aim to answer the question of whether those tests help reduce the overall mortality rate in asymptomatic individuals. For now, liquid biopsy techniques cannot fully replace mammography, which means that a negative test does not guarantee that a person has not had cancer.

The current standard: imaging and biopsy

Mammograms are the best form of detection, using low-level X-rays to identify potentially suspicious changes, often prior to any lumps being felt. Depending on age, medical conditions, and predisposition, it is often suggested by professionals to undergo an ultrasound or MRI scan. Suspicious findings are usually traced through biopsy examined via microscope gadgets.

Who should consider screening?

The type of screening schedule you follow will depend on your age, family history, personal medical history, and inherited genetic mutations like BRCA1 and BRCA2. If someone is at greater risk, they may require earlier or more specialised screening. Red flags may include a new growth in the breast or underarm, changes in breast size or shape, skin dimpling, inverted nipples, or unusual discharge from the nipples. Those who experience these signs should get themselves evaluated by a physician instead of just waiting for a blood test.

Looking ahead

NGS-based liquid biopsy is seeing advancement in the detection of blood-based breast cancer. With the development of sensitivity and evidence collected from the trial, it is possible that it may be used in addition to mammography, mainly for people who are at higher risk or for people facing obstacles to imaging. Before that happens, however, it is still advisable to monitor one’s risk level and keep following the authorised screening rules and procedures.

The author is the Head of Research and Development and Academics at Metropolis Healthcare Limited. 

 

The opinions expressed in this article are those of the author and do not purport to reflect the opinions or views of THE WEEK. 

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