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Page 2 of 3 Zhang. J Cancer Metastasis Treat 2021;7:22 https://dx.doi.org/10.20517/2394-4722.2021.82

biopsy or integration with sensitive and complementary ctDNA technologies may be the key for the
practice-changing implementation of liquid biopsy in managing early breast cancer. Endometrial cancer,
[3]
another women’s cancer, is the focus of a review by Malentacchi et al. . Endometrial cancer is usually
detected at low stage with a good prognosis, though some cases can evolve to bad prognosis. However, there
is no molecular target for treatment, detection, or monitoring. Through a comprehensive review of
[3]
molecular targets in liquid biopsies, Malentacchi et al. discussed how these approaches may help in the
management and characterization of patients affected by endometrial cancer. Cancer-derived exosomes
carry a unique set of DNA, RNA, protein and lipid that may serve as diagnostic biomarkers. Specifically,
Happel et al. reviewed scientific highlights in biomarker discovery of exosome-based extracellular RNA
[4]
(exRNA) in human cancers. Their review suggested that exRNA is useful not only for liquid biopsies to
diagnose various cancer types, but it also provides potential avenues for therapy. Numerous new
technologies are being developed for liquid biopsy-based diagnosis. Su et al. were particularly interested in
[5]
magnetic nanotechnologies that possess many advantages such as low background noise, high sensitivity,
short assay time, and the ability to detect multiple biomarkers at the same time. Specifically, Su et al.
[5]
focused their discussion on the recent advances of magnetic nanotechnologies in liquid biopsies for
sensitive, efficient, and portable cancer diagnosis.

Both of the original articles focused on lung cancer. Rath et al. investigated a new mechanism of drug
[6]
resistance for small-cell lung cancer (SCLC) circulating tumor cells (CTCs). They measured cellular
fragments in SCLC CTC cell lines and compared to permanent SCLC lines. Their findings suggested that
generation of cell-associated debris by SCLC CTCs may offer protective effects against cytotoxic drugs,
representing a novel mechanism allowing survival of SCLC CTCs in patients. In comparison,
Udukala et al. described their pilot study of early detection of non-small cell lung cancer (NSCLC) in
[7]
liquid biopsies by ultrasensitive protease activity analysis. Specifically, using a case-control design, they
presented promising results for the feasibility of minimally-invasive early diagnosis of NSCLC by protease
biomarkers in the sera derived from peripheral blood.

During the past decade, the research community has achieved tremendous advances in cancer early
diagnosis with liquid biopsy-based approaches. Future investigations will ultimately prove the utility of
these novel approaches in improving clinical outcomes of cancer patients.

DECLARATIONS
Authors’ contributions
The author contributed solely to the article.

Availability of data and materials
Not applicable.

Financial support and sponsorship
This work was partially supported by grants from the National Institutes of Health: R01CA223662,
R21MD011439, and U01CA217078.

Conflicts of interest
The author is a shareholder of Shanghai Epican Genetech Co. Ltd, which develops liquid biopsy-based
cancer biomarkers. This article is not related to the company.