Use of cold-atmospheric plasma in oncology: a concise systematic review

Abstract

Background: Cold-atmospheric plasma (CAP) is an ionized gas produced at an atmospheric pressure. The aim of this systematic review is to map the use of CAP in oncology and the implemented methodologies (cell targets, physical parameters, direct or indirect therapies).

Methods: PubMed, the International Clinical Trials Registry Platform and Google Scholar were explored until 31 December 2017 for studies regarding the use of plasma treatment in oncology (in vitro, in vivo, clinical trials).

Results: 190 original articles were included. Plasma jets are the most-used production systems (72.1%). Helium alone was the most-used gas (35.8%), followed by air (26.3%) and argon (22.1%). Studies were mostly in vitro (94.7%) and concerned direct plasma treatments (84.2%). The most targeted cancer cell lines are human cell lines (87.4%), in particular, in brain cancer (16.3%).

Conclusions: This study highlights the multiplicity of means of production and clinical applications of the CAP in oncology. While some devices may be used directly at the bedside, others open the way for the development of new pharmaceutical products that could be generated at an industrial scale. However, its clinical use strongly needs the development of standardized reliable protocols, to determine the more efficient type of plasma for each type of cancer, and its combination with conventional treatments.

Keywords: neoplasms; nonthermal atmospheric pressure plasma; oncology; plasma jet; review.

Figure 1.

Geographical distribution and type of the included studies. (a) Cumulative histogram of the evolution over years of the number of articles and reviews; (b) proportion of articles and reviews by year; only original articles and reviews were included (n = 220); (c) geographical distribution of the included studies; each author’s nationality was recorded; consequently, a study may be related to several countries.

Figure 2.

Evolution of the number of studies dealing with dielectric barrier discharge or plasma jet over time. Only nonreview articles were included (n = 190); studies could be considered in multiple categories.

Figure 3.

Yearly distribution of the articles according to the type of carrier gas. Only nonreview articles were included (n = 190), a study could be considered in multiple categories.

Figure 4.

Cumulative histogram of the evolution over the years of the number of articles according to the type of cancer studied. (a) Human cancers; (b) murine cancers. Only nonreview articles were included (n = 190); studies could be considered in multiple categories.