Use of permanent interstitial temperature self-regulating rods for ablation of prostate cancer

Background and Purpose: We have examined a new technique for the thermal tr eatment of prostate cancer involving the percutaneous placement of small ma gnetic alloy rods into the gland in a procedure analogous to the placement of permanent brachytherapy seeds. When the patient and the implanted rods a re placed in an extracorporeal alternating magnetic field, the rods heat an d can produce tissue necrosis. The rods are temperature self-regulating and produce temperatures no higher than their preprogrammed regulation value. The rods are biocompatable permanent implants, comprised of cobalt and pall adium, Materials and Methods: We examined rods that heat to 55 degrees, 60 degrees , and 70 degrees C. Patients are treated for 1-hour sessions and easily hav e multiple sessions. Results: Isolated rods produced little or asymmetrical necrosis, However, a rrays of 70 degrees C rods placed within 1 cm of each other caused consiste nt necrosis between the rods. The temperature at the edge of the array drop ped off quickly, and therefore, the rods can be placed within 2 mm of the c apsule even posteriorly near the rectum, Conclusions: Arrays of high-temperature rods can be employed for tissue abl ation, while lower-temperature arrays could be used to produce hyperthermia in order to achieve synergism with adjuvant radiation therapy. The techniq ue is applicable in an outpatient setting.