What is Liquid Biopsy? How is Liquid Biopsy Performed?

Cancer is one of the significant health problems threatening human health today, and extensive efforts are being made to find a solution. Despite various diagnostic and treatment methods used so far, an effective method for curing cancer has not yet been established. For this reason, numerous research studies on cancer are being conducted internationally, utilizing various technologies for diagnosis and treatment. One of these methods is liquid biopsy.

What is Liquid Biopsy?

Cancer arises primarily due to the formation of certain abnormalities in the body’s healthy cells, influenced by various genetic and environmental factors. Cells with disrupted biological structures not only proliferate uncontrollably but also behave contrary to the body's physiological processes, acquiring an unnatural tissue structure. Over time, these proliferating cells form masses called tumors and develop their own vascular structures. At this point, cancer cells gain new properties, enabling them to spread to other parts of the body, and they begin to move into the bloodstream.

The process of detecting and examining these circulating cancer cells or the DNA belonging to these cells from blood samples taken from patients is referred to as liquid biopsy. Similar to routine blood tests that measure different biochemical substances in the blood, specific amounts of blood samples are collected from patients, and various methods are employed to detect cancer cells. The identified cancer cells can then be further characterized using additional techniques.

In the presence of tumor tissue, it is essential to demonstrate the cancer cell through pathological examination for a definitive cancer diagnosis. The commonly used method for this involves removing the entire tumor tissue or a portion of it and sending it for pathological examination. During this examination, cancer cells are isolated and identified using various techniques. This method is known as tissue biopsy and histopathological examination.

Tissue biopsy can be performed directly in clinical settings with various equipment or during imaging procedures like endoscopy, or it can be conducted during surgical operations to remove the tumor. Additionally, another method called needle aspiration biopsy is used, especially for tumors showing cystic structures, where tissue content is obtained with a needle, and cancer cell detection is performed through cytological examination. The difference here is that although cancer cells can be shown from the obtained tissue content, the tissue structure cannot be preserved. Liquid biopsy, however, differs from these two methods. With its various advantages, liquid biopsy provides detailed and valuable information to the physician that cannot be obtained through the other two methods, while also offering ease of application and comfort to the patient.

What is the Purpose of Liquid Biopsy?

The purposes of liquid biopsy can be defined as follows:

Firstly, the presence of tumor tissue and the possibility of accessing that tissue are essential for performing tissue biopsy or needle biopsy. Therefore, it allows for the detection of cancer in the advanced stages when tumor masses are formed, which can be laborious to apply and may require serious interventions like surgery. On the other hand, liquid biopsy enables the early detection of cancer cells even before a tumor mass has developed, following a routine and straightforward procedure similar to standard blood tests.

In early-stage cancer, where cancer cells cannot yet be detected, isolating only the cancer DNA in the bloodstream provides very valuable information for diagnosis and treatment planning. It allows for the characterization of obtained cancer cells, enabling more effective treatment methods to be applied. It assists in making the correct drug choice based on the detected biological characteristics of the cancer. It also allows for measuring the effectiveness of the applied treatment.

When is Liquid Biopsy Performed?

Liquid biopsy is preferred in conditions where normal tissue biopsy cannot be applied, where existing cancer may arise in another part of the body, or when the information obtained from tissue biopsy is insufficient for diagnosis and treatment planning. Due to its ability to be easily repeated and the valuable genetic and biochemical data it provides, liquid biopsy is an important method in diagnosis and treatment decisions.

Research has shown that liquid biopsy is particularly beneficial for the following types of cancer:

• Breast cancer
• Lung cancer
• Gastrointestinal cancer
• Pancreatic cancer
• Cervical, Endometrial, Ovarian, and Fallopian tube cancers
• Kidney cancer
• Bladder cancer
• Melanoma
• Brain tumors
• Testicular tumors
• Leukemia and Lymphomas (blood cancer)
• Other rare epithelial tumors

Liquid biopsy can be used in the diagnosis of various cancer types, and it can also be utilized to indicate the presence of recurrence in cancers at risk of recurrence after treatment. Furthermore, it provides useful information in planning the treatment of these diseases and evaluating the response to treatment.

How is Liquid Biopsy ?

Liquid biopsy is performed by taking a specific amount of blood sample from the patient, similar to routine blood tests. The collected blood sample is examined for the following parameters to obtain the necessary data for diagnosis and treatment:

• Detection of circulating cancer cells: The isolation of the small amounts of cancer cells that have entered the bloodstream is achieved through various methods. The obtained cells can be analyzed in detail using targeted techniques for various characteristics.
• Detection of DNA samples belonging to cancer cells: Since the cancer cells that enter the bloodstream continue to divide rapidly, they can break down and transfer their contents into the blood plasma at certain intervals. One of the most important substances in this content is the DNA sample of the cancer cell. The DNA of the cancer cell is isolated from the blood obtained through liquid biopsy, and various analyses can be performed to obtain valuable information, including cancer diagnosis, characterization of the cancer, treatment planning based on DNA characteristics, and determining and monitoring the response to treatment.

Structural and functional cellular changes specific to cancerous cells can be detected and investigated in-depth from circulating tumor cells (CTCs) or the DNA shed from these cells, meaning the material obtained through liquid biopsy.

What are the Benefits of Liquid Biopsy?

There are several advantages provided by the application of liquid biopsy. These advantages can be listed as follows:

• Compared to the serious interventions and invasive techniques used in tissue biopsy, liquid biopsy is a straightforward and effective procedure involving minimal intervention.
• It is a less expensive procedure compared to tissue biopsy and pathological examination.
• It provides very valuable information about the genetic and biological infrastructure of the tumor, which is extremely useful in determining the method used in treatment and evaluating the response to treatment.
• Because it can be easily applied and repeated, it allows for monitoring changes in cancer cells that occur in response to drug resistance during treatment. Tissue biopsy, being diagnostic only, cannot offer a similar benefit.
• Since the samples obtained from tissue biopsy are examined only after undergoing special chemical processes, they are not suitable for studying the genetic structure of cancer cells. On the other hand, liquid biopsy allows for the detection and detailed examination of DNA from cancer cells present in the blood.
• While the pathological examination of tissue biopsy can take weeks, the results of liquid biopsy can be determined in a much shorter time.

What is the Future of Liquid Biopsy?

Currently, one of the popular research topics is genetic studies and gene therapy. Since the basis of cancer is genetically linked, advancements in this area of research are groundbreaking for cancer diagnosis and treatment.

It can be said that liquid biopsy will gain more importance in light of current genetic research. This is because the genetic map of cancer cells in circulation can be derived from the results of liquid biopsy. Thus, potential target regions for gene therapy can be identified, making it possible to completely eliminate cancer with effective gene therapy. Similarly, resistance mechanisms developed by cancer against the treatment methods used can be addressed, leading to significant progress in cancer treatment.

If you would like more detailed information about liquid biopsy, you can visit our hospital to seek assistance from specialist physicians.