A prototype of a flexible grid electrode to treat widespread superficial tumors by means of Electrochemotherapy

Abstract

BackgroundIn recent years, superficial chest wall recurrence from breast cancer can be effectively treated by means of electrochemotherapy, with the majority of patients achieving response to treatment. Nevertheless, tumor spread along superficial lymphatic vessels makes this peculiar type of tumor recurrence prone to involve large skin areas and difficult to treat. In these cases, electroporation with standard, small size needle electrodes can be time-consuming and produce an inhomogeneous coverage of the target area, ultimately resulting in patient under treatment.Materials and methodsAuthors designed and developed a prototype of a flexible grid electrode aimed at the treatment of large skin surfaces and manufactured a connection box to link the pulse applicator to a voltage pulse generator. Laboratory tests on potato tissue were performed in order to evaluate the electroporation effect, which was evaluated by observing color change of treated tissue.ResultsA device has been designed in order to treat chest wall recurrences from breast cancer. According to preliminary tests, the new flexible support of the electrode allows the adaptability to the surface to be treated. Moreover, the designed devices can be useful to treat a larger surface in 2–5 minutes.ConclusionsAuthors developed the prototype of a new pulse applicator aimed at the treatment of widespread superficial tumors. This flexible grid needle electrode was successfully tested on potato tissue and produced an electroporation effect. From a clinical point of view, the development of this device may shorten electrochemotherapy procedure thus allowing clinicians to administer electric pulses at the time of maximum tumor exposure to drugs. Moreover, since the treatment time is 2–5 min long, it could also reduce the time of anesthesia, thus improving patient recovery.

Recent Advances in Electrochemotherapy

“…The third large area of preclinical research is dealing with different types of electrodes that can be used in vitro, in vivo, or in humans, that is, grid, single needle, or endoscopic, [59][60][61][62][63][64] with different types (e.g., sine wave pulses, pulsed electromagnetic field, and high-frequency short bipolar pulses), and parameters of electric pulses (amplitude and frequency). [65][66][67][68][69] The overall aim of these studies is to provide new electrodes that will be able to reach/treat the tumors that are not accessible with the current electrodes that are on the market and to provide electrodes that will not induce pain, muscle contraction, and/or skin burns, that is, undesired side effects that are commonly reported in clinical studies on electrochemotherapy.…”

Electric field distribution study in inhomogeneous biological tissues

“…Typically, electrodes with needles arranged in a bilinear geometry with a gap of 4 mm or in a hexagonal geometry with a gap of 7 mm are usually used to treat the tumors . Hence, this type of electrodes is able to cover a small surface (few cm 2 ), and they require multiple applications for treating larger areas, thus extended time of operation and theater and sedation of the patient . To alleviate this, a large grid electrode has been designed and developed .…”

“…1,12,13 Hence, this type of electrodes is able to cover a small surface (few cm 2 ), and they require multiple applications for treating larger areas, thus extended time of operation and theater and sedation of the patient. 14 To alleviate this, a large grid electrode has been designed and developed. [14][15][16] However, since a larger area is covered by the grid electrode, there is tissue inhomogeneity to be taken into account for the application of electrochemotherapy on large areas, like chest wall carcinoma after mastectomy.…”

“…14 To alleviate this, a large grid electrode has been designed and developed. [14][15][16] However, since a larger area is covered by the grid electrode, there is tissue inhomogeneity to be taken into account for the application of electrochemotherapy on large areas, like chest wall carcinoma after mastectomy. 2,3 Because of scars and variable amounts of extraneous tissues, including blood vessels and their contents, connective tissues, necrotic and dead cells, fat, and other inhomogeneities in the solid tumors, including irregular vascularization, pH variations, and heterogeneous oxygen concentration, 17 the remaining surface could have tissue inhomogeneity, since different tissues show different resistivity value at nonelectroporated condition.…”

Effect of Electrode Distance in Grid Electrode: Numerical Models and In Vitro Tests

“…Currently, the delivery of a sequence of 96 pulses with a period of 200 microseconds (pulse duration 100 microseconds at 5 kHz 6 , 7 ), using existing voltage pulse generator, requires at least 20 milliseconds only for pulse delivery. 10 However, at this time, it is necessary to add the time to move electrode, to charge capacitance (eg, 5-6 seconds), and to manually activate discharge, which for each 96-pulse sequence has to be considered at least 20 seconds long. In this way, in order to treat a surface of 200 cm2, the time interval required is at least 40 minutes.…”