Background and objectives: Ablation is an alternative
nonsurgical local treatment, which is used for in situ destruction of solid
tumors. We developed pulse alternate electric current based treatment for
in-situ tumor ablation (Pulsed Electric Current Tumor Ablation-PECTA), which
effectively eliminated primary tumors by low currents conducted through one or
more thin electrodes. PECTA may affect the tumor tissue by a number of
different mechanisms such as: pH changes, electric field, heat, gas formation
and free radicals. In this study we examined the electrical properties essential for PECTA.
Methods:
Balb/c mice bearing subcutaneous tumors were treated by PECTA or surgery
as control. Two tumor types were tested: the weak immunogenic mammary
adenocarcinoma (DA3) and the immunogenic colon carcinoma (CT26). PECTA was
applied by intratumoral electrodes delivering 25-100 coulomb per electrode per
cm3 (C/E/cm3) of tumor tissue. The efficiency of ablation
was tested by measuring the elimination of the primer tumor and prevention of local
or marginal recurrence
Results: First we
demonstrated that ablation efficiency by pulsed current (PECTA) was superior to
continuous current. Next we found that efficient and predictable tumor
destruction can be achieved by controlling the coulomb delivered to the tumor. An
optimal result of ~ 100% cure level was obtained when 100 C/E/cm3
were transferred to the tumor. An important and interesting finding was that
the ablation efficiency was dependent on the electrode charge (polarity) inserted
into the tumor. When using the same coulomb per tissue mass, the anode was more
effective for tumor ablation than the cathode: For colon adenocarcinoma (CT26)
and breast carcinoma (DA3) tumors the cure level by the anode was about twice
than the cure level achieved by the cathode. Electric current treatment by
anode and cathode together had an intermediate effect on both tumor types.
Conclusions: These
findings suggest an alternative simple, powerful and affordable ablation tool
for treating solid tumors.
