It has been known for a long time that normal cellular functions will stop if the temperature is raised to 42°C/108°F, and that large-scale cell death--necrosis--will occur at temperatures above 46°C/115°F. Killing cells with heat presents a possible  method of cancer treatment; measures must be taken to minimize the heating of surrounding healthy cells.

Radiofrequency ablation (RFA) is an invasive procedure that uses electrical pulses to heat a probe that is placed in a tumor.  The probe can be a single, straight rod-like structure or it can be a hollow rod that contains several smaller wires.  Once inserted into the tumor, the smaller wires can be pushed out to reach a larger amount of the tumor.Widmann G, Bodner G, Bale R. Tumour ablation: technical aspects. Cancer Imaging. 2009 Oct 2;9 Spec No A:S63-7. [PUBMED]Gillams A. Tumour ablation: current role in the kidney, lung and bone. Cancer Imaging. 2009 Oct 2;9 Spec No A:S68-70. [PUBMED]

RFA can be performed in an open procedure with full anesthesia or by insertion of the probe through the skin.  Placement of the probe can be guided by ultrasound, magnetic resonance imaging (MRI) and/or computer assisted tomography (CAT or CT). After the treatment, the cells in the tumor will die, leaving behind only a scar.

Cancers treated with RFA include liver cancerJarnagin WR. Management of small hepatocellular carcinoma: a review of transplantation, resection, and ablation. Ann Surg Oncol. 2010 May;17(5):1226-33. Epub 2010 Apr 20. [PUBMED]Laeseke PF, Frey TM, Brace CL, Sampson LA, Winter TC 3rd, Ketzler JR, Lee FT Jr. "Multiple-electrode radiofrequency ablation of hepatic malignancies: initial clinical experience." AJR Am J Roentgenol. 2007 Jun;188(6):1485-94. [PUBMED], metastatic colorectal cancerWong SL, Mangu PB, Choti MA, Crocenzi TS, Dodd GD 3rd, Dorfman GS, Eng C, Fong Y, Giusti AF, Lu D, Marsland TA, Michelson R, Poston GJ, Schrag D, Seidenfeld J, Benson AB 3rd. American Society of Clinical Oncology 2009 clinical evidence review on radiofrequency ablation of hepatic metastases from colorectal cancer. J Clin Oncol. 2010 Jan 20;28(3):493-508. Epub 2009 Oct 19. [PUBMED], lung cancerCasal RF, Tam AL, Eapen GA. Radiofrequency ablation of lung tumors. Clin Chest Med. 2010 Mar;31(1):151-63, Table of Contents. [PUBMED]Simon CJ, Dupuy DE, DiPetrillo TA, Safran HP, Grieco CA, Ng T, Mayo-Smith WW. "Pulmonary radiofrequency ablation: long-term safety and efficacy in 153 patients." Radiology. 2007 Apr;243(1):268-75. [PUBMED]Gadaleta C, Mattioli V, Colucci G, Cramarossa A, Lorusso V, Canniello E, Timurian A, Ranieri G, Fiorentini G, De Lena M, Catino A. "Radiofrequency ablation of 40 lung neoplasms: preliminary results." AJR Am J Roentgenol. 2004 Aug;183(2):361-8. [PUBMED] and kidney (renal) cancer.Joniau S, Tailly T, Goeman L, Blyweert W, Gontero P, Joyce A. Joniau S, Tailly T, Goeman L, Blyweert W, Gontero P, Joyce A. J Endourol. 2010 May;24(5):721-8. [PUBMED]

RFA can be performed more than one time if additional tumors arise.
The effectiveness of the procedure compared to surgical removal of tumors is still being determined.Jarnagin WR. Management of small hepatocellular carcinoma: a review of transplantation, resection, and ablation. Ann Surg Oncol. 2010 May;17(5):1226-33. Epub 2010 Apr 20. [PUBMED]Wong SL, Mangu PB, Choti MA, Crocenzi TS, Dodd GD 3rd, Dorfman GS, Eng C, Fong Y, Giusti AF, Lu D, Marsland TA, Michelson R, Poston GJ, Schrag D, Seidenfeld J, Benson AB 3rd. American Society of Clinical Oncology 2009 clinical evidence review on radiofrequency ablation of hepatic metastases from colorectal cancer. J Clin Oncol. 2010 Jan 20;28(3):493-508. Epub 2009 Oct 19. [PUBMED]

More information on this topic may be found in Chapter 16 of The Biology of Cancer by Robert A. Weinberg.

A Closer Look at Killing Cancer Cells with Heat

In a study conducted on mice engineered to contain human breast cancer cells examined the use of nanoprobes targeted to tumor cells as a method to direct heat  to a tumor. Anti-tumor antibodies were linked to very small spheres containing iron oxide pellets. Injection of these 'bioprobes' led to binding of the particles on the surface of the tumor cells.

The chemical nature of the iron in the complexes causes them to rotate rapidly when an alternating magnetic frequency (AMF) is applied in the vicinity of the tumor. The spinning motion generates heat that quickly raises the temperature of tumor cells above 46°C/115°F, causing death of the tumor cells. For this technique to be useful, it is critical that the applied frequency is not harmful to surrounding tissues.

In the mouse experiments the applied treatment significantly decreased tumor growth. Importantly, the affect was proportional to the amount of heat delivered via AMF. The most effective, non-toxic treatment corresponded to low amplitude AMF with a prolonged delivery time. Since this study was performed, new nanoparticles have been developed that respond better to AMF potentially reducing the amount of AMF necessary to treat tumors. Sally J. DeNardo, Gerald L. DeNardo, Arutselvan Natarajan, Laird A. Miers, Allan R. Foreman, Cordula Gruettner, Grete N. Adamson, and Robert Ivkov. "Thermal Dosimetry Predictive of Efficacy of 111In-ChL6 Nanoparticle AMF Induced Thermoablative Therapy for Human Breast Cancer in Mice." Journal Nuclear Medicine 2007 48: 437-444. [PUBMED]