Surgical implant therapy involves the placement of small radiation seeds, chemotherapy wafers, or both seeds and wafers in a cavity after a tumor has been removed. The seeds and/or wafers remain in the cavity permanently.
Radiation seeds are about the size of grains of rice. They consist of titanium casings containing low-radioactivity iodine 125. After a tumor’s removal, about 50 to 100 seeds are placed in the surgical cavity, where they remain permanently. They give an effective radiation dose over a period of six months. They continuously emit radiation during that timeframe, thus killing remaining microscopic tumor cells in the surrounding brain.
Studies performed at UC have demonstrated the safety of permanent seed implants to both the patient and the surrounding environment (i.e., loved ones) and have shown their ability to control brain tumors for extended periods of time. Radiation seeds are currently used for metastatic tumors and recurrent malignant gliomas, glioblastoma and Grade 3 gliomas.
Chemotherapy wafers, which are about the size of a nickel, also can be placed in a surgical cavity after a tumor has been removed. They are made of a polymer that has been filled with the chemotherapy agent carmustine (BCNU).
Pioneering research at the UC Brain Tumor Center, published in the Journal of Neurosurgery, revealed that the simultaneous implantation of radioactive seeds and chemotherapy wafers in patients with recurrent glioblastoma was well tolerated by patients and provided longer survival compared with the implantation of seeds or wafers alone.
A second trial, published in the Journal of Neuro-Oncology, demonstrated that this strategy was not effective in patients newly diagnosed with glioblastoma because of increased toxicity. Currently, the strategy of seeds and wafers is used for patients with recurrent glioblastoma who have failed initial treatment.