Clinical experience with cold plasma in the treatment of locally advanced head and neck cancer

Purpose: Cold atmospheric pressure plasma (CAP) is well known for inactivating microbial pathogens and stimulation of tissue regeneration in chronic wounds. Several authors have reported the effectiveness against cancer in different cell lines and animal models. This is the first report of patients with real clinical benefit following application of CAP, not just visible change of the tumor surface but lasting partial remission. The authors discuss the CAP treatment approach and the efficacy for inoperable head and neck cancer patients. Methods: The trial enrolled six patients with locally advanced (pT4) squamous cell carcinoma of the oropharynx suffering from open infected ulcerations. Patients were treated with a jet plasma source (kINPen MED, neoplas tools GmbH, Greifswald, Germany) in cycles of 3 single applications (1 min/cm² from a distance of 8 mm) within 1 week, each followed by an intermittence of 1 week. Results: CAP treatment resulted in a reduction in odor and pain medication requirements, in improvement in social function and a positive emotional affect. Further observance revealed partial remission in two patients for at least nine month. Incisional biopsies at remission demonstrate a moderate amount of apoptotic tumor cells and a desmoplastic reaction of the connective tissue. Conclusion: The trial demonstrates the clinical relevance of CAP in cancer treatment. There are three approaches for discussion of tumor remission: (i) the role of myeloid cells, (ii) the ROS/RNS model of cellular impact and (iii) the immunogenic cell death model of cancer treatment, and there is a reflection on non-sustainable tumor response due to adapted tumor microenvironment.