and spares healthy tissue, new research suggests.
The results showed inserting a collagen matrix containing radioactive seeds into the brain postsurgery did not impede wound healing. It also showed a favorable safety profile, researchers note.
Benefits for patients undergoing this GammaTile (GT) intervention include not having to wait weeks to receive radiation treatment, which in turn improves their quality of life, said study investigator Clark C. Chen, MD, PhD, chair, department of neurosurgery, University of Minnesota Medical School, Minneapolis.
“These initial results are highly promising and offer hope for patients afflicted with an otherwise devastating disease,” Dr. Chen said in an interview.
If replicated in larger trials, GT therapy “could define a new standard of care, and there would really be no reason why patients shouldn’t get this therapy,” he added.
This is the first clinical series describing GT use since its approval by the U.S. Food and Drug Administration (FDA) for recurrent brain cancer.
The findings were presented at the annual meeting of the American Association of Neurological Surgeons (AANS) and were published recently in Neuro-Oncology Advances.
Radioactive seeds
GT therapy is a version of brachytherapy where radioactive sources are placed adjacent to cancerous tissue. It consists of radioactive seeds embedded with a collagen tile.
The neurosurgeon inserts these “tiles” immediately after tumor removal to cover the entire resection cavity, Dr. Chen said. The tiles maintain the cavity architecture to prevent radiation “hot spots” associated with cavity collapse.
Dr. Chen noted the therapy is “short range,” with most of the radiation delivered within 8 millimeters of the radioactive seeds.
The radiation lasts for about a month and the collagen tiles are eventually absorbed within the body. “You put in the tiles and you don’t need to do anything more,” Dr. Chen said.
GT has a number of advantages. Unlike with traditional brachytherapy, the collagen tile provides a buffer around the radiation sources, allowing delivery of the optimal radiation dose while preserving healthy tissue.
It also avoids the up-to-6-weeks patients have to wait postsurgery to get external beam radiation therapy. “If you start radiation too early, it actually compromises wound healing, and in the meantime the tumor is growing,” said Dr. Chen.
“I have several patients where I removed a large tumor and within that 6-week period, the tumor came back entirely,” he added.
With the gamma-tile, however, radiation from the seeds kills the tumor while the body heals.
Safety profile
The study included 22 patients (mean age, 57.7 years; 15 men, 7 women) with wild-type isocitrate dehydrogenase glioblastoma. They were all having surgery for recurrent tumors.
“One of the most challenging aspects of glioblastomas is that not only do the tumors come back, they come back immediately adjacent to where you have done the surgery, and for many patients this is demoralizing,” Dr. Chen said.
Six participants had 0 6 -Methylguanine-DNA methyltranferase (MGMT) methylated glioblastoma, while the others had unmethylated MGMT.
The mean follow-up from initial diagnosis was 733 days (2 years).
Results showed one patient had to be readmitted to the hospital for hydrocephalus, but there were no re-admissions within 30 days attributable to GT.
Despite participants having undergone a second and third resection through the same surgical incision, there were no wound infections. “One of the concerns of giving radiation right after surgery is it can compromise wound healing, and this is why you wait 6 weeks,” Dr. Chen noted.
He stressed that no patient in the study suffered from adverse radiation effects that required medical or surgical intervention.
As the radiation is so short-range, hair loss and skin irritation are not side effects of GT, he added.
“The radiation is inside the brain and highly targeted, so it doesn’t hit hair follicles,” said Dr. Chen. “As best as I can observe in these patients, I did not see toxicity associated with radiation.”