# Cold Atmospheric Pressure Plasma in Wound Healing and Cancer Treatment
## 2 CAP Treatment to Promote Healing of Acute and Chronic Wounds
This meta-analysis, however, included only four of the above-discussed studies [9; 10; 11; 16]. In these studies, three different CAP sources have been used, and studies investigating the effects of CAP on chronic wounds, as well as on acute wounds, have been included. Particularly, the study by [PERSON] and colleagues, which assessed wound size as the primary endpoint and showed a significant effect of the CAP treatment, was not included in the meta-analysis. Further evidence for a positive effect of CAP on wound healing comes from a recently published prospective, randomized, placebo-controlled, blinded, multi-centered study, including 65 chronic wounds of 45 patients with diabetic leg ulcers [18]. While all patients received standard wound care, 33 wounds were treated additionally with eight applications of CAP (kINPen MED, neoplasms tools GmbH, Greifswald, Germany), and the other 32 wounds were treated with placebo (argon gas flowing through the kINPen MED device without ignition of plasma). This randomized clinical trial revealed a significantly stronger reduction in wound size and accelerated time to relevant wound area reduction. Interestingly, no significant difference in the reduction of infection and the microbial load was observed between CAP and placebo groups. This suggests that improved wound surface reduction and time to wound closure was independent of background infection [18]. Similar results were presented from another recent randomized clinical trial assessing the use of CAP (plasma jet, self-constructed) to treat diabetic foot ulcers [19]. Patients were randomly and double-blinded assigned to one group receiving standard care alone, and another group receiving standard care and CAP (22 patients per group). Primary endpoints were wound size and bacterial load. It was found that CAP significantly accelerates wound healing of diabetic foot ulcers. Immediate antiseptic effects have been observed as well, but these do not seem to last long [19]. Although the here discussed studies and several single case-reports show beneficial effects of CAP on wound healing in general, not every patient benefits from the treatment. Hence, more research is needed to optimize CAP treatment regarding the type of plasma source, plasma treatment time, and plasma treatment intervals. Furthermore, it is conceivable that parameters, such as age, smoking, alcohol consumption, or body-mass-index, play a significant role regarding the efficacy of the treatment. Further comprehensive studies will bring about further insights on parameters that may have a positive or negative influence on CAP treatment success and thus may help to stratify patients before treatment. \begin{table}
\begin{tabular}{l l l l} \hline \hline \multicolumn{1}{c}{**Plasma Source**} & **Treatment of** & **Number of Participants** & **Reference (Year)** \\ \hline MicroPlaSter \(\alpha\) & Chronic wounds & 36 & [6] (2010) \\ CPC 1500 System (jet) & Pleural mesothelioma & 8 & [20] (2010) \\ MicroPlaSter \(\alpha\)/\(\beta\) & Chronic wounds & 24 & [7] (2012) \\ kINPen & Acute wounds & 5 & [13] (2012) \\ MicroPlaSter \(\alpha\)/\(\beta\) & Chronic wounds & 70 & [10] (2013) \\ MicroPlaSter \(\beta\) & Acute wounds & 34 & [16] (2013) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Clinical trials and case reports of CAP application for treatment of chronic and acute wounds, as well as (pre-)cancerous tissues.