PITTSBURGH, November 11, 1998 — University of Pittsburgh researchers have found that stereotactic radiosurgical treatment of acoustic tumors provides long-term tumor control, high rates of neurologic function preservation and patient satisfaction, according to a study in the Nov. 12 issue of the New England Journal of Medicine.
"Stereotactic radiosurgery is the primary alternative to microsurgical resection of acoustic tumors. Prior to the understanding of the long-term effects of radiosurgery, some physicians and patients questioned the ability of radiosurgery to provide long-term prevention of tumor growth," said Douglas Kondziolka, M.D., co-director of the Center For Image-Guided Neurosurgery at the University of Pittsburgh Medical Center (UPMC), professor of neurological surgery and radiation oncology and principal author of the study.
"With the study, we have now shown that patients with newly diagnosed, or residual or recurrent small- or medium-sized tumors are suitable candidates for radiosurgery. Although acceptable short-term outcomes were reported, up until now, longer-term patient outcomes were less well-documented."
An acoustic neuroma grows on the eighth cranial nerve which is responsible for transmitting balance and hearing information to the brain from the inner ear. They cause symptoms such as hearing loss, balance problems, tinnitus, vertigo and headache. This is one of the most common benign brain tumors with two to three thousand new cases annually.
Patients underwent radiosurgery with the gamma knife, which performs precise, computer-driven bloodless brain surgery. It destroys tumors and vascular malformations, which were once considered inoperable. Gamma knife surgery is safer than many existing procedures because patients need not undergo risky open-skull procedures, and adult patients do not require general anesthesia. Gamma knife surgery causes few side effects, and patients usually leave the hospital within 24 hours.
The study evaluated 162 patients with acoustic tumors who underwent radiosurgery between 1987 and 1992. Outcomes after five and ten years were determined through the use of imaging studies, physician-based evaluations and a patient survey.
The study found that the clinical tumor control rate was 98 percent and normal facial function was preserved in 77 percent of patients. Radiosurgery was believed successful by all 30 patients who had undergone prior surgery. Five to ten years after radiosurgery, 97 percent of surveyed patients believed that radiosurgery provided a satisfactory outcome for their acoustic tumor.
"In our study, 98 percent of patients required no further surgery and 94 percent had imaging confirmation of persistent tumor control. Five patients had transient tumor enlargement that was followed by shrinking," Dr. Kondziolka said. "Although one cannot state that the radiosurgery control rate is better than or similar to the surgical cure rate, because the tumor mass remains in the radiosurgery patients, both treatments seemed to provide a similar rate of prevention from problems of further tumor growth."
Co-authors of the study are L. Dade Lunsford, M.D., F.A.C.S; Lars Leksell professor of neurological surgery, chairman of the department of neurological surgery at the University of Pittsburgh, professor of radiation oncology, professor of radiology and chief of neurological surgery at University of Pittsburgh Medical Center; John C. Flickinger, M.D., professor of radiation oncology in the department of radiation oncology; and Mark McLaughlin, M.D., chief neurosurgery resident.