Epidermal Growth Factor Receptor Status Offers Potential for Meningioma Treatment

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Newswise — Meningioma is typically a benign tumor of the meninges, the tissue that covers and surrounds the brain and spinal cord. It is one of the most common intracranial tumors and accounts for up to 26 percent of all adult brain tumors. Based on examination of tumor tissue microscopically, pathologists distinguish three different grades of meningioma that help predict the clinical behavior of the tumor, facilitate treatment planning, and enable an estimate of overall patient prognosis. These include grade I (benign), grade II (atypical), and grade III (malignant), comprising approximately 80 percent, 15 percent, and 5 percent of meningiomas, respectively.

In the vast majority of meningiomas studied, receptors for specific growth factors have been identified on the surface of the tumor cells. These growth factors are normally produced by the body and facilitate growth and maintenance of normal cells. However, tumor cells can overexpress the same receptors, which contribute to their abnormal growth by enabling these cells to utilize the corresponding growth factors. Because multiple growth factor receptors have been identified on subsets of meningiomas, neurosurgeons recently studied whether the presence or absence of these receptors on atypical meningioma tumor specimens may help predict whether the corresponding tumors will follow an indolent or aggressive clinical course.

The results of this study, Absence of Epidermal Growth Factor Receptor Immunoreactivity Defines a Subset of Atypical Meningiomas with a Distinctly Poor Prognosis, will be presented by Justin S. Smith, MD, PhD, 5:03 to 5:15 p.m. on Wednesday, April 26, 2006, during the 74th Annual Meeting of the American Association of Neurological Surgeons in San Francisco. Co-authors are Anita Lal, PhD, Mianda Harmon-Smith, BS, and Michael W. McDermott, MD.

While benign meningiomas can often be cured if they are located in areas in which they can be surgically removed in their entirety, malignant meningiomas are usually fatal within several years of diagnosis. The clinical behavior of the intermediate-grade atypical meningiomas is much more variable, and controversy exists on how these tumors should be treated after surgery. The clinical course of atypical meningioma ranges from indolent, with normal or nearly normal lifespan, similar to that of benign meningiomas, to aggressive, with rapid progression and death within months to a few years, similar to malignant meningiomas. "The ability to predict what course a patient with an atypical meningioma will follow can provide invaluable information which may equate to a more accurate prognosis and optimal treatment strategy," stated Dr. Smith.

This study assessed the presence of three different growth factor receptors in 90 meningioma tumors, which were comprised of 29 benign, 30 atypical and 31 malignant tumors. Additionally, it was noted whether each patient was alive or deceased at last follow-up, and if deceased, how long the patient had survived following diagnosis. The mean follow-up period was nine years. One of the receptors studied proved to be particularly interesting. This receptor, the epidermal growth factor receptor (EGFR), enables cells to use a powerful growth factor called epidermal growth factor (EGF). EGFR was identified in approximately one-half of the atypical meningiomas studied. Whether EGFR was present in each tumor was then compared with the length of survival of the corresponding patient. Among atypical meningioma patients, the presence of EGFR proved to be a remarkably powerful predictor of prolonged patient survival following diagnosis. This association was not evident in patients with benign or malignant meningiomas.

"In conclusion, EGFR status is a significant predictor of survival among atypical meningioma patients," concluded Dr. Smith. A combined assessment of pathology and EGFR status may hold promise for enabling physicians to provide patients with meningiomas with more accurate prognoses and optimal treatment strategies.

Founded in 1931 as the Harvey Cushing Society, the American Association of Neurological Surgeons (AANS) is a scientific and educational association with more than 6,800 members worldwide. The AANS is dedicated to advancing the specialty of neurological surgery in order to provide the highest quality of neurosurgical care to the public. All active members of the AANS are certified by the American Board of Neurological Surgery, the Royal College of Physicians and Surgeons (Neurosurgery) of Canada or the Mexican Council of Neurological Surgery, AC. Neurological surgery is the medical specialty concerned with the prevention, diagnosis, treatment and rehabilitation of disorders that affect the entire nervous system, including the spinal column, spinal cord, brain and peripheral nerves.