Scientific background: Electrochemotherapy is an inventive approach to cancer treatment. Howevwer, only a few studies so far have focused on its role in the treatment of skin and mucosal head and neck cancers. Properly designed and well-conducted prospective clinical trials are required to determine the efficiency and safety of electrochemotherapy in this group of patients. Technological improvements implement electrochemotherapy as a feasible treatment also for deep-seated head and neck tumors. Nevertheless, intravenously administrated bleomycin is currently the most utilized drug for electrochemotherapy, but it might have some specific side effects, predominantly lung fibrosis and possible ulceration in the treated areas. The main parameters of bleomycin pharmacokinetics need to be determined in order to provide optimal effectiveness and safety of electrochemotherapy. Furthermore, the role of tumor microenvironment in bleomycin distribution and its consequential impact on tumor response to electrochemotherapy has to be explained.
Aim: The aim of the study was to evaluate the effectiveness and safety of bleomycin-based electrochemotherapy in the treatment of head and neck cancer. Specific objectives were: (i) to determine an optimal time frame between bleomycin injection and electroporation and optimal bleomycin concentration required for effective electrochemotherapy, (ii) the improvement of technological procedure in the treatment of deep-seated head and neck tumors and (iii) determination of predictive factors for effective electrochemotherapy.
Hypothesis: Electrochemotherapy is an effective and safe treatment modality for the treatment of head and neck cancer.
Methods: In the scope of the study, the local anti-cancer effectiveness and safety were followed on the skin and mucosal head and neck cancers treated with electrochemotherapy. The efficiency of electrochemotherapy as a treatment option of deep-seated head and neck tumors was evaluated by coupling treatment planning and navigation system. The parameters of bleomycin pharmacokinetics were determined in patients and in vivo in mice by liquid chromatography coupled with high-resolution mass spectrometry. Tumor microenvironment on carcinoma and melanoma tumor models was additionaly investigated with immunohistochemical analysis.
Results: The evaluation of treatment outcome in patients with head and neck cancer treated with electrochemotherapy confirms the efficacy and safety of electrochemotherapy in this group of patients. The optimized technological approach enables the treatment of deep-seated tumors in the head and neck region. In the group of elderly patients, therapeutic window is prolonged compared to younger patients and a reduced dose of bleomycin is equally effective as a standard dose. The tumor response to electrochemotherapy is influenced by tumor vascularization, which affects bleomycin distribution in the tumor.
Conclusion: Electrochemotherapy proved to be an efficient and safe treatment of cancers in different head and neck regions. The results of the study broaden therapeutic options in the treatment of head and neck cancer and contribute to the adaptation of the electrochemotherapeutic protocols to each individual patient. Characteristics of tumor microenvironment are an important predictive factor to the tumor response to electrochemotherapy.