Hyperthermia
Hyperthermia has been proposed as a cancer treatment, and published evidence confirms that hyperthermia is effective in treating diseases like cancerous growths. It is understood that malignant cells are reliably more sensitive to heat than normal cells. The therapeutic benefit of hyperthermia therapy is mediated through two principal mechanisms: (1) a directly tumoricidal effect on tissue by raising temperatures to greater than 42.degree. C., resulting in irreversible damage to cancer cells; and (2) hyperthermia sensitizes cancer cells to the effects of radiation therapy or to certain chemotherapeutic drugs. The lack of any cumulative toxicity associated with hyperthermia therapy, in contrast to radiotherapy or chemotherapy, further suggests the desirability of developing improved systems for hyperthermia therapy. While considerable success has been observed in treating superficial tumors using hyperthermia therapy, there remains a need for a method of selectively targeting and treating diseased tissue in a patient.
A large fraction of a tumor's mass is made of hypoxic (poorly oxygenated) cells. Hypoxic cells are much more resistive to radiation therapy than euoxic (well oxygenated) cells. It has been reported that when heat and a radiosensitizing agent (e.g., misonidazole) are used in combination with each other, they produce synergistic potentiation effects. See Schneiderman, et al., Radiat. Res. 155:529-35 (2001); Billi, et al., Appl. & Environm. Microbiology 66: 1489-92 (2000); and Hofer, "Hyperthermia and Cancer," 4.sup.th Int. Conf. Scientific and Clinical Applications of Magnetic Carriers, Tallahassee-Fla., pp. 78-80 (2002). In Hofer's report, hypoxic cancer cells subjected to the two agents during irradiation showed a response enhanced by a factor of 4.3, which far exceeded the euoxic cells. However, Hofer's whole body heating approach is not optimal for clinical application on human, because whole-body heating limits the heat dose that can be given. It would be more desirable to provide a combination therapy in which only the tumor region is heated, i.e., selective hyperthermia.
Recent US Patents
11/30/2010
7,842,281
Magnetic particle composition for therapeutic hyperthermia
Haik and Chen of the Florida State University, Florida, have developed magnetic nanoparticle which are heated by an alternating magnetic field. The magnetic particles are produced by ball milling and encapsulated in a biocompatible polymer. The suspended particles are injected into the blood stream, surrounding tissues or directly into a cancerous tumor. The localized magnetic field heats up the particles either releasing anticancer drugs or destroying directly the cancerous cells by heating. (RDC 4/19/2011)