This article was originally published in the November/December 2014 issue of the “Advances” newsletter from NewYork-Presbyterian Hospital.
In October, NewYork-Presbyterian/Weill Cornell Medical Center completed its conversion to frameless, non-invasive stereotactic radiosurgery for its Novalis radiosurgery program.
“Weill Cornell is at the forefront of the field for treating benign and malignant pathologies of the central nervous system using stereotactic radiosurgery,” says Philip E. Stieg, MD, PhD, Neurosurgeon-in-Chief, NewYork-Presbyterian/Weill Cornell and Chairman of the Weill Cornell Brain and Spine Center. “Frameless stereotactic radiosurgery eliminates the need to attach a frame to a patient’s skull, and the beauty of this approach is that it is equally as precise as all of the other radiation devices, it’s faster, less complex, pain free, and more comfortable for the patient.”
Radiosurgery stands as a unique field in medicine, drawing on the disciplines of neurosurgery, radiation oncology, and medical physics. At Weill Cornell, Susan C. Pannullo, MD, Director of Neuro-oncology and Neurosurgical Radiosurgery, and A. Gabriella Wernicke, MD, MSc, a radiation oncologist who leads the Cancer Therapy Program in the Department of Radiation Oncology and is a member of the Weill Cornell Brain and Spine Center, work in concert to plan and execute their patients’ treatment plans.
“Susan and I have a perfect marriage of two specialties – neurosurgery and radiation oncology – with a specific focus on the delivery of stereotactic radiosurgery treatments,” says Dr. Wernicke, whose academic and clinical interests have contributed new insights into the approach, delivery, and outcomes of radiotherapy. “Our combined efforts in building the stereotactic radiosurgery program began in 2010, and since its inception, we have introduced a number of novel treatment options for patients with a wide variety of tumors.”
Their pioneering collaborations, along with Weill Cornell colleagues, have addressed a number of hypofractionated stereotactic protocols for patients with meningioma, including a National Cancer Institute’s SEER (Surveillance, Epidemiology, and End Results) analysis of adjuvant external-beam radiotherapy (EBRT) outcomes for nonbenign meningiomas published in the Journal of Neurosurgery in 2012. This was the first population-based analysis examining the effect of adjuvant EBRT on outcomes in patients with nonbenign meningiomas. The study underscored the need for randomized prospective clinical trials to assess the usefulness of adjuvant EBRT and to define more precisely the subset of patients who may benefit from the addition of adjuvant radiation treatment in Grade II/III meningiomas.
Today radiosurgery has become a key component in the neurosurgical armamentarium. In the last decade, improvements in imaging and computing have led to the development of image-guided frameless radiosurgery, a precise noninvasive variant offering improved patient comfort and treatment flexibility in addition to radiosurgical accuracy. It is used for patients with diagnoses that include brain metastases, glioblastomas, meningiomas, acoustic neuromas, and a variety of benign and malignant spinal tumors.
Transitioning to Frameless SRS
“We are entering a new phase of brain tumor treatment,” notes Dr. Pannullo, a neurosurgeon and a neuro-oncologist and one of the few neurosurgeons in the world with a neurosurgical practice focused only on stereotactic radiosurgery. “The transition to frameless radiosurgery marks the end of an era for our frame-based stereotactic radiosurgery program. The Novalis system enables us to treat tumors of the brain and spine, as well as other conditions, with highly focused beams of radiation that minimize exposure of normal brain and spine structures and achieve a level of accuracy comparable to frame-based radiosurgery. ExacTrac® technology, a component of Novalis, is a monitoring system that provides miniature images during the course of treatment that track any patient movement and allow for the machine to compensate by repositioning its beams.”
In conventional frame-based radiosurgical approaches, the patient is immobilized with a head frame affixed to the skull and positioned before treatment by inferring the location of internal anatomy from external coordinates provided during the localization process. “In the past, a patient was bolted into a head-holder that was screwed into the skull to prevent movement,” says Dr. Pannullo.
“The frameless approach utilizes a head-to-shoulder immobilizing, removable mask that is extremely patient friendly,” says Dr. Wernicke. “We achieve absolute precision with targeting while delivering high doses, and at the same time sparing the normal structures. Precision-driven software, which makes adjustments based on the boney anatomy on the order of submillimeters automatically, detects intra-fractional tumor motion during the treatment delivery. This allows us to deliver single or multi-fraction treatment in the most precise manner possible and to identify the tumor target live in real-time with real-time verification.”
“If there is any small movement within the breathable, plastic face mask, it is detected,” notes Dr. Pannullo. “The beams, which come from multiple angles, reposition to account for any movement.”
“Efficiency is an important attribute for any image-guided radiotherapy system, especially given the growing patient demand for radiation therapy,” adds Dr. Wernicke. “One method to improve efficiency is to provide a more automated approach for the patient set-up and treatment. This novel technology provides either 4-D or a full 6-D robotic alignment. Furthermore, it allows us to condense the number of treatments from one to five fractions.” Treatments, delivered on an outpatient basis, range from half an hour to 45 minutes.
In addition to providing the latest in radiosurgical techniques, the Weill Cornell team has developed unique protocols not available elsewhere for the treatment of various tumors that further reduce the overall treatment time. “For instance, we treat meningiomas from the benign to atypical to malignant types with one to five fractions of radiotherapy within a week’s time,” says Dr. Wernicke. “This essentially avoids the previously utilized protocols of five to six weeks of five-day-a-week radiation. Our results are equivalent, if not superior, to the standard fractionation protocol used in other centers.”
Both Drs. Wernicke and Pannullo cite the importance of the multidisciplinary nature of radiosurgery. “This frameless technology, in particular, allows us to work as a group to deliver the best treatment to patients with a range of conditions of the brain and spine,” says Dr. Pannullo. “It is a team effort by a neurosurgeon and a radiation oncologist along with physicists and radiation therapists. The neurosurgeon’s primary role is to outline the area that is to be treated, and also to define the areas that are to be avoided during the treatment. The primary role of the radiation oncologist is to determine the appropriate dosing and directly oversee the treatment. The physicist helps to construct the safest and most optimal treatment plan, which is then approved by the neurosurgeon and the radiation oncologist.”
“We work together to develop the treatment plan, execute the treatments, follow patients in their after-treatment care, and review their results in our weekly multidisciplinary Brain and Spine Tumor Board,” says Dr. Wernicke.
As radiosurgery becomes more and more a part of brain tumor and spine treatment, Dr. Pannullo notes that she will meet with the neurosurgeon who is performing open surgery preoperatively to develop a combined treatment approach. “The advantage is that the neurosurgeon can then go into the OR with a plan to leave a portion of tumor that would otherwise be very risky to remove with the knowledge that I can follow up with radiosurgery on that remaining piece of tumor,” says Dr. Pannullo. “An adaptive hybrid surgery analysis is built into the Novalis system, enabling us to bring the benefits of both approaches to maximize the treatment outcome.”
More about the Stereotactic Radiosurgery Program at Weill Cornell
