What is a liquid biopsy?
During the growth of a tumor, some tumor cells break away from the tumor and enter the bloodstream, where they are then circulated throughout the body. These tumor cells that are free in the blood are called “circulating tumor cells,” or CTCs for short because the English name is circulating tumor cell.
Tumor cell fragmentation is a process in which tumor cells are fragmented and then spread throughout the body.
Also, when a tumor cell breaks down, it releases the genetic material, or DNA, from its nucleus into the bloodstream, and this circulating tumor cell DNA is called “circulating tumor DNA.
When a tumor cell is broken down, it also releases its genetic material in the nucleus, or DNA, into the bloodstream, and this circulating tumor cell DNA is called “circulating tumor DNA.
Although CTC and ctDNA were discovered decades ago, it is only in the last few years that tests for these two substances have been introduced into clinical use.
A small amount of blood is taken and analyzed for CTC and ctDNA components to obtain a large amount of molecular genetic information about the tumor in what has become known as a “liquid biopsy”. Currently, more liquid biopsy techniques are used for ctDNA.
Can liquid biopsies be used to diagnose thyroid cancer?
Can a liquid biopsy be used to diagnose thyroid cancer?
Currently, the gold standard for thyroid cancer diagnosis is still pathology, not liquid biopsy results.
While doctors do not use liquid biopsies as a diagnostic standard, ctDNA may be used to help patients choose a more appropriate therapy.
We’ve heard the term tumor markers, and there are several common indicators for thyroid cancer, but all fall short. For differentiated thyroid cancer, thyroglobulin (Tg) is often used as a marker to monitor recurrence after total thyroidectomy. However, both benign and malignant tissues can secrete Tg, so the specificity is greatly reduced. In addition, thyroglobulin antibodies (TGAb) are present in 25% of patients and bind to Tg. In this case, Tg levels do not accurately reflect the tumor. The screening markers for medullary thyroid cancer are serum calcitonin (CT) and carcinoembryonic antigen CEA, but they are also not tumor-specific.
In contrast, ctDNA is slightly better in terms of tumor specificity. A recent UK study hypothesized that detectable ctDNA could be used as a prognostic marker for thyroid cancer and be useful for subsequent individualized treatment. The study suggests that ctDNA is useful when several commonly used tumor markers are unreliable. Therefore, ctDNA may be useful as a complement to currently used markers. In addition, the study suggests that ctDNA predicts disease progression earlier and with more confidence than commonly used markers, especially for medullary carcinoma. For patients receiving targeted therapies, ctDNA may offer even more benefits – faster assessment of whether the treatment is working and helping physicians select drugs.
We hope that the results of this small study will be further confirmed and applied to the clinic soon.