We Do Not Recommend Liquid Biopsy for Early Cancer Diagnosis in Healthy Individuals! Why?

With advances in genetic science, cancer genesare being identified and analyzed more rapidly. For this purpose, liquid biopsies are being studied to detect circulating tumor DNA fragments in the blood and analyze these DNA fragments for use in planning cancer treatment. Let us answer common questions about the use of liquid biopsy in cancer treatment.

What Is Liquid Biopsy?

Liquid biopsy is a non-invasive cancer analysis method, meaning it does not involve an invasive procedure or surgery. In liquid biopsy, a blood sample is taken from the patient, and circulating tumor cells, cell fragments and their DNA are analyzed. The aim of liquid biopsiesis to detect certain genetic materials, primarily DNA, that cancer cells release into the blood.

Is There Any FDA Approval for Liquid Biopsy Tests?

On 1 June 2016, the FDA EGFR mutation approved the first liquid biopsy test for use together with the test. This test non-small cell lung cancer are suitable for the EGFR-targeted drugs erlotinib and osimertinibis used to determine whether these patients are suitable for these drugs. Note carefully: FDA approval of liquid biopsy is not for diagnosing cancer, but for determining the cancer subtype and whether a targeted smart drug will be effective in a patient who already has a cancer diagnosis! The test was developed to detect certain mutations in exon 19 or exon 21 of the EGFR gene, namely mutations . These mutations occur in 10 to 20 percent of patients with non-small cell lung cancer.

Can Liquid Biopsy Tests Be Used for Early Cancer Diagnosis?

Approval for using liquid biopsies in early cancer diagnosis, from either the FDA or any international body regulating medical practice, has not been granted! According to the latest published studies, using liquid biopsy for early cancer diagnosis is not possible with today’s technology!

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What Factors Prevent the Use of Liquid Biopsies for Early Cancer Diagnosis?

1. Studies of liquid biopsy tests for early cancer diagnosis have found high rates of incorrect results. Cancer development was not observed in people in whom circulating tumor DNA was detected.
2. Liquid biopsy tests may identify early-stage tumors that would not harm the patient. This may lead to unnecessary or excessive treatment. More sensitive liquid biopsy tests with proven accuracy are needed.
3. Liquid biopsies aim to detect established cancer biomarkers. For most cancer types, a well-defined biomarker does not exist. This makes it difficult to use liquid biopsies for the early diagnosis of different cancer types.
4. DNA damage may differ between patients with the same cancer type. In addition, different DNA damage occurs at different stages in the same patient. This creates a need to develop different liquid biopsy tests for each cancer type and stage.
5. Circulating tumor DNA fragments do not reflect the entire DNA structure of the tumor tissue. Tumor tissue is highly heterogeneous (mixed). In other words, DNA damage differs among cancer cells within the same tumor tissue. This makes it difficult to use liquid biopsy tests for clinical interpretation.
6. No study has shown that liquid biopsy procedures contribute to patients’ survival. Therefore, prospective (forward-looking) studies investigating the clinical effectiveness of liquid biopsies are needed.
7. Whether mutations detected in circulating tumor DNA fragments are passenger or driver mutations cannot be determined. This prevents effective clinical interpretation.
8. DNA damage differs among patients with the same cancer type. DNA damage may also vary according to the type and stage of cancer. This is one of the important factors making cancer diagnosis through liquid biopsy difficult.

Liquid Biopsy – Is Early Cancer Diagnosis Through Blood Tumor DNA Screening a Major Deception?

The most important factor determining success in cancer treatment is undoubtedly early cancer diagnosis. Despite major advances in imaging methods in recent years, many cancer types still cannot be diagnosed early enough to improve success sufficiently. Detecting cancer at an early stage through a simple blood test taken from healthy individuals is one of the most important endeavors and aspirations of the entire scientific community. Performing certain tests on circulating tumor cells or tumor particles, particularly in people diagnosed with advanced cancer, has made our daily practice easier. Some of these tests guide us in determining the course of disease and selecting treatment.

In individuals who have been diagnosed with and treated for cancer, cancer recurrence (relapse) may be detected through liquid biopsy during follow-up, which may be useful. Comprehensive studies are also needed in this field to change routine practice. However, for the reasons explained above, attempting to diagnose cancer at an early stage through liquid biopsy in healthy individuals who have never had a cancer diagnosis remains no more than a dream. We do not consider it right to mislead a society living in fear of cancer by presenting this as an accomplished reality.

In conclusion, liquid biopsies may play an important role in planning cancer treatment and monitoring the course of disease. However, their use for “early diagnosis” of cancer is not currently possible.

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