July 22, 2005

Noninvasive radiotherapy effective for ear tumors

An MGH research team has shown that stereotactic radiotherapy (SRT) is a safe and effective treatment for patients with vestibular schwannomas — non-malignant tumors affecting nerves supplying the inner ears. Patients with these tumors, which also are called acoustic neuromas, may develop hearing loss and balance problems. Advanced cases can proceed to facial weakness or paralysis and, if critical brain structures are affected, may be life-threatening.

In a follow-up to a 1996 study, Annie Chan, MD, of MGH Radiation Oncology, and her colleagues report in the July issue of Neurosurgery the largest study of this application of SRT with the longest follow-up. "Our results show that SRT provides a tumor control rate of 98 percent at five years, which is comparable to that of the best surgical and radiosurgical series," says Jay Loeffler, MD, chief of MGH Radiation Oncology and the senior author of the paper.

SRT delivers highly focused radiation over a six-week course of treatment and, in contrast to surgery and radiosurgery, is noninvasive. Information from CT and MR imaging studies is used to carry out three-dimensional treatment planning, and a noninvasive stereotactic frame immobilizes the patient's head during radiation to assure precise treatment delivery.

"In addition to the excellent tumor control rate, SRT results in very low treatment-related side effects," says Chan. "In our study, none of the patients developed new facial weakness, and in patients who already had facial weakness, the rate of worsening over five years was only 1 percent. No additional tumor development or malignant transformation was seen for up to 10 years after treatment." The paper's MGH co-authors are Frederick Barker, MD, Hanne Kooy, PhD, Robert Martuza, MD, and Robert Ojemann, MD.