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Pastor et al. J Cancer Metastasis Treat 2020;6:39 I http://dx.doi.org/10.20517/2394-4722.2020.57 Page 7 of 9

that helps us study the tumor more accurately. Liquid biopsy is one of the advanced methods that will soon
help to diagnose tumors earlier and also to follow their morphological development, making treatment
more precise than in the past. It might not replace the X-ray, MRI and CT scan because it is still essential
to know where precisely the tumor grows, but once the tumor is visible, it is more likely to be associated
with an adverse prognosis. With the help of liquid biopsy, we can diagnose the tumor much earlier and
thus decrease the need for chemotherapy, which may be useful for cancer therapy in the advanced stage but
may have many side effects for the patient. Thus, we could achieve a better result with the help of a liquid
biopsy.

Every tumor is individually different. The liquid biopsy helps us track down its morphological development
earlier and, in this way, helps us to control it better and enables us to develop a treatment according to its
genetic profile. This is what we call precision medicine. Exosomes can be released by both immune cells and
non-immune cells. They have immunomodulatory properties. EX lead to signalling in T-cells and in other
immune cells. The primary mechanism is the uptake of exosomes and the release of non-coding RNAs,
[8]
especially microRNAs which play a part in the regulation of RNA translation . TEX regulate immune cells
by the direct interaction between Fas and Fas-ligand, which causes cell death of activated CD8 cytotoxic
[8]
T-cells . Exosomes seem to have multiple effects on the immune system. As such they transport pro- and
anti-tumorigenic as well as pro- and anti-inflammatory signals to target cells. Depending on the target cell,
[8]
for example, dendritic cells, T lymphocytes or B cells, exosomes may send clear signals .
Due to their various properties, exosomes are an exciting target for therapeutic and diagnostic aims.
Tumor cells are known to produce numerous exosomes. In the plasma of HNSCC patients, exosomes are
enormously increased in comparison to healthy patients. Their profile difference makes them attractive
[8]
to be used in liquid biopsy analysis . Cancer treatment such as immunotherapy in HNSCC patients
is being conducted in clinical practice currently. First data on using exosomes as tumor biomarkers in
HNSCC have been reported [17,30] . However, more data are needed on the features of circulating exosomes
in HNSCC patients. Many investigations on exosomes in cancer treatment as well as the first keen results
[44]
have been published . Many more studies will be carried out on this topic and time will tell which of these
approaches will lead to a better outcome in patient care.

DECLARATIONS
Authors’ contributions
Literature research and writing the paper: Pastor K
Figure design: Benecke L
Study idea in design: Muller L

Availability of data and materials
Not applicable.

Financial support and sponsorship
This work was supported by Propatient (pp18-08).

Conflicts of interest
All authors declared that there are no conflicts of interest.

Ethical approval and consent to participate
Not applicable.