Radiofrequency Ablation
Although partial nephrectomy is the established treatment for renal cancers, less invasive procedures such as radiofrequency ablation (RFA) have emerged. RFA may be indicated in patients when renal tumors are less than 4cm diameter, or when resection is not possible.
RFA is an outpatient procedure with the patient under conscious sedation. Using CT guidance, a radiofrequency electrode is inserted into the tumor. Once in place, metal tines deploy to penetrate and surround the tumor and induce coagulation in a controlled fashion. A high frequency alternating current of 500 kHz is applied and maintained until irreversible cell damage has been achieved, with temperatures reaching 100 degrees C. The necrotic tissue remains in the body. Over time, it is absorbed and replaced 
with scar tissue or excreted like other waste products. Because RFA emits a form of non-ionizing, electromagnetic energy, it does not change the molecular makeup of cells like other cancer therapies.
Patients require follow up imaging with a CT or MRI one month after the procedure to assess its success. Annual checkups are also recommended. Although some patients may require a second ablation, the necessity to do so is less than 10 percent when tumors are less than 3 cm.
The program at BIDMC uses a three-pronged strategy for improving thermal ablation in clinical practice: in-vivo animal studies in which selected ablation parameters can be systematically modulated; mathematical 
and computer modeling; and translation of experimental gains into clinical studies. We have into clinical studies. We have also been exploring the use of RFA with more conventional methods such as chemotherapy and radiation and have demonstrated the beneficial effect of combining thermal therapy with liposomal doxorubicin to improve tumor coagulation and achieve%ulation and achieve maximum synergy.
Top image: Radiofrequency ablation is a less invasive option offered at BIDMC for treating patients with metastic disease. RFA of centrally located renal tumor measuring 4.5 by 3.5 cm.
Middle image: Before treatment, tumor (red arrow) reveals contrast enhancement on CT imaging. Gas vapor is seen along the needle shaft (arrowheads), indicating the intensity of heat and tissue vaporization.
Bottom Image: RFA was performed using a cooled cluster electrode (black arrow). The 18-month follow-up reveals no tumor enhancement, suggesting complete treatment (white arrow). Bright enhancement (black arrow) reveals intact functional calyces after treatment. Perirenal fat necrosis is observed (arrowheads).
