Side effects in cold plasma treatment of advanced oral cancer—Clinical data and biological interpretation

Purpose

Treating oral cancer with cold atmospheric plasma (CAP) is an evidence-based-medicine level III concept in ongoing cancer research. There is a discussion concerning the potential risk in medical application of CAP due to the formation of free radicals, which may have an adverse impact. After in recent studies the risk of dramatic effects like genotoxic impact was basically excluded, the focus of this discussion is mainly on acute unwanted clinical effects.

Methods

A retrospective analysis is including 20 patients suffering from locally advanced head and neck cancer and contaminated ulcerations, who underwent palliative treatment with CAP for decontamination. The focus lies on documented side effects related to CAP.

Results

There are no, mild or moderate unwanted effects related to the application of CAP, especially never life threatening.

Conclusion

Understanding the lack of severe side effects in plasma medicine, the role of radical oxygen species (ROS) and radical nitrogen species (RNS) is discussed, proposing a model in which CAP is not a direct effector of antitumor action but rather triggers a singlet oxygen-mediated switch-on effect on the specific target, leading to reactivation of intercellular ROS/RNS-dependent apoptosis signaling in tumor cells. As these processes are strictly restricted to the specific targets and as normal tissue is devoid of the required target, it is neither harmed nor affected.