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Show Therapy Studied for Effect on Cancer has been used in certain settings to produce tumor regressions. "Increasing our ability to contgrol the primary tumor and its spread to regional lymph nodes remains an important element in progress toward decreasing morbidity and mortality of cancer," says Dr. Gibbs. "We have considerable hope that hyperthermia will improve our ability to cope with this aspect of cancer treatment." Heat as a means of increasing in-creasing the effectiveness of x-ray therapy in the treatment treat-ment of cancer is being investigated at University of Utah Medical Center. "We are heating tumors in certain patients with a technique that is similar to diathermy treatment administered ad-ministered for minor athletic injuries," explains Dr. Frederic A. Gibbs, Jr., assistant professor of radiology and director of the University's first pilot clinical study on hyperthermia. hyper-thermia. "The essential difference in the heating process is that we are able to much more accurately control the treatment with our sophisticated equipment." equip-ment." The Medical Center's laboratory research into the effects of heat on cancer, developed by Dr. Gibbs and his colleagues over the past , four years, is rapidly expanding ex-panding and already has earned national attention. The recently initiated clinical program has awaited : the availability of an . instrument capable of carefully controlling the heating process. The sophisticated microwave apparatus used in the clinical trial-one of only two presently available in the nation-was developed by BioSystems Design . Corporation in the University Research Park, in collaboration with the U Department of Engineering. Since the in-, in-, strument was installed a month ago, several patients have begun treatment with combined heat and x-ray therapy. To be a candidate for , the experiemental procedure, patients must have tumors for which conventional treatments are either impossible or unlikely to be helpful. The tumors must also be within roughly two inches of the skin surface. sur-face. A half dozen other institutions in-stitutions have done pilot hyperthermia studies on a total of, several hundred patients, with encouraging results. "We know from laboratory animal and cell culture experiments that heat will augment the tumor-killing effects of x-ray, x-ray, though we still have concerns about the possibility of normal tissue damage as well," says Dr. Gibbs. "In most clinical cases reported we would have expected only a moderate shrinkage of the tumor mass with conventional con-ventional x-ray or chemotherapy. But by combining hyperthermia and x-ray tratments, a fair number of patients have had striking regressions in the tumor size; sometimes even total disappearance." The equipment used for heating in many of the studies done at other cancer centers has been primitive in comparison with the Utah-produced Utah-produced instrument used by Dr. Gibbs and his colleagues. . "Having both the instrument's developers and members of the University's electrical and bioengineering departments close at hand will facilitate ongoing development of tumor-heating technology," . says Dr. Gibbs. Here's how the procedure works: Microwaves are carried through a coaxial cable into a small metal box call "wave-guide applicator," ap-plicator," suspended immediately im-mediately over the tumor. Heat-producing microwaves are transmitted from this box into the tumor. Special temperature monitoring probes are inserted into the tumor and surrounding tissues following administration ad-ministration of local anesthetic to numb the area. Temperature measurements from these probes are fed back to a computer control mechanism which automatically maintains the tumor at a preset temperature. A specially shielded procedure room keeps microwaves from interfering in-terfering with com-munications com-munications radio frequencies. In an adjacent room a technician follows the course of the treatment from the computer console. The console's TV screen allows continuous visual monitoring of the patient and voice communication is maintained over an intercom. in-tercom. Tumor temperture is . generally maintained at 43 to 44 deg. C (109 to 111 deg F) for one-half hour and the treatment is repeated twice weekly in conjunction with x-ray therapy. "The treatment generally produces a sensation of extreme warmth," explains Dr. Gibbs. "Pain is not commonly experienced until a skin temperature of 45 deg. C is reached. The 43 - 44 deg. we administer is not painful. Increased discomfort can occur, however, as a result of swelling in a tumor that is already painful." Dr. Gibbs emphasizes that the treatment is promising but as yet unproven and that technical considerations limit its use. "For certain patients whose clinical circumstances cir-cumstances meet our present criteria for treatment, treat-ment, hyperthermia does appear to offer a new hope," Dr. Gibbs adds, "but we don't want to raise false hopes and expectations for the overwhelming majority of cancer patients. In addition ad-dition to our uncertainty about the ultimate efficacy and potential complications of the treatment, we are presently limited in our ability to deliver heat any deeper than five to six cm. However, research underway un-derway should provide a ' means of heating at greater depths." The technique also has considerable promise when used in conjunction with chemotherapy, according to Dr. Gibbs, and heat by itself |