Treatment Approach Shows Promise Against Glioblastoma
An innovative treatment approach may offer improvement in overall survival in older patients with newly diagnosed glioblastoma while maintaining quality of life. Results of Mayo Clinic's phase 2, single-arm study are published in The Lancet Oncology.
Sujay Vora, MD, radiation oncologist at Mayo Clinic, led a team of researchers investigating the use of short-course hypofractionated proton beam therapy incorporating advanced imaging techniques in patients over the age of 65 with newly diagnosed World Health Organization (WHO) grade 4, malignant glioblastoma.
Results showed that 56% of participants were alive after 12 months and the median overall survival was 13.1 months." As compared to prior phase 3 studies in an older population having a median survival of only six to nine months, these results are promising," says Dr Vora. "In some cases, patients with tumors that have favorable genetics lived even longer, with a median survival of 22 months. We are very excited about these results."
Glioblastoma is among the most challenging cancers to treat. The disease invades healthy brain tissue with hairlike tentacles, making surgical removal intricate. Surgeons must carefully balance removing as much of the tumor as possible while avoiding harm to critical areas of the brain responsible for essential functions such as movement and speech. Additionally, the tumor's cellular composition and its ability to evade therapies further challenge treatment efforts.
Standard radiation therapy is commonly used to treat glioblastoma and can be effective. However, a limitation is that it also exposes healthy brain tissue to radiation, potentially causing collateral, unintended damage. For the Mayo Clinic study, investigators used one of the most innovative and advanced forms of radiation treatment, called proton beam therapy. The cutting-edge, nonsurgical form of radiation therapy destroys cancer cells with targeted precision while minimizing side effects to surrounding healthy tissue.
Mayo investigators mapped the target area in the patient's brain by combining the advanced imaging technologies, including 18F-DOPA PET and contrast-enhanced MRI. "Combining advanced imaging allowed us to determine the most metabolically active, or aggressive, regions of the glioblastoma," says Dr Vora.
Treatment was completed in one to two weeks instead of the traditional three to six weeks. "The advanced imaging along with the proton beam therapy allowed us to be more focused with radiation and protect surrounding healthy brain tissue from the effects of radiation. We were able to see that patients tolerated the treatments well and lived longer than we expected."
According to Dr Vora, the study at Mayo Clinic is the first clinical trial of its kind investigating the use of short-course hypofractionated proton beam therapy incorporating advanced imaging technology, including 18F-DOPA PET and contrast-enhanced MRI targeting, for patients 65 and older with newly diagnosed glioblastoma.
William Breen, MD, radiation oncologist and principal investigator of the current study says it is too early to draw any conclusions about the safety and efficacy of the treatment until the study is complete. "Our goal is to transform the way we treat glioblastoma using shorter courses of radiation to minimize the burden on patients and their families and help them complete safe and effective treatment in a shorter amount of time."
The clinical trial, known as SAGA, or stereotactic ablative radiation treatment for glioblastoma, includes patients from Arizona, Florida and Minnesota. "We are now adding another component that builds upon Dr Vora's work to help us best visualize the tumor," says Dr Breen.