By Jason T. Shumadine, MD
New radiation techniques for patients with multiple brain metastases significantly reduce treatment times and, thanks to extremely precise delivery and dosing, spare more healthy tissue to avoid troubling side effects.
While cancers of various origins can spread to the brain via the bloodstream, the majority of systemic treatments such as chemotherapy and immunotherapy generally are unable to cross the semipermeable blood-brain barrier in high enough amounts to control cancer growth.
Therefore, the vast majority of these patients require either surgery or radiation. Surgery, of course, is not always a viable option due to a lesion’s location within the brain or the presence of more than one cancerous growth.
Not long ago, the standard of care was to treat a patient’s entire brain with radiation in hopes of destroying existing lesions and preventing new growth.
However, data that has emerged over the past decade suggests patients will fare better with more targeted treatments, which aim to limit the loss of cognitive abilities and/or memory function.
One powerful new weapon is HyperArc High-Definition Radiotherapy. This advanced form of stereotactic radiosurgery builds on the breakthrough success of the CyberKnife System, an effective and noninvasive method of delivering tailored radiation doses from multiple angles.
Unlike older machines, the rotating HyperArc system can irradiate multiple tumors simultaneously. This is a critical difference for patients with brain metastases, who typically have more than one tumor. Most commonly, in fact, a patient will present with three to five lesions; in one case, I counted more than 50.
Irradiating a single lesion once took up to an hour, requiring many patients to spend hours at a treatment center or spread appointments over several days. New equipment has reduced those times to five to 10 minutes per spot, often confined to a single day of treatment.
Radiation beams also are increasingly compact and fitted to each lesion’s size, shape and location, thanks to guidance from advanced scans and computerized calculations.
For patients who still need a more whole-brain treatment approach due to their type or stage of disease, another critical advance within the past several years is volumetric modulated arc radiotherapy (VMAT).
VMAT is a form of intensity modulated radiotherapy (IMRT). Yet instead of stopping and starting between target areas, VMAT machines rotate around the patient in a continuous arc for greater efficiency.
Additionally, VMAT limits radiation to the hippocampus, the central brain region that plays a major role in learning and memory. Clinical trials have shown that this approach – whole-brain radiation with hippocampal sparing – benefits cognitive function two years later.
Both of these newer therapies can be performed in conjunction with systemic treatments, albeit with careful coordination and monitoring of side effects. It has been gratifying to help more patients not only survive longer but enjoy a better quality of life.
Dr. Shumadine is a Radiation Oncologist with Virginia Oncology Associates. He is trained in all major modalities of radiation therapy for cancer treatment and is active in clinical oncology research. virginiacancer.com