Although external beam radiation therapy is effective in the treatment of many pediatric brain neoplasms its use in this patient population has been associated with the development of significant cognitive and endocrine dysfunction and is severely limited as an option in previously irradiated patients. Therefore, we have adopted a strategy for management of residual microscopic disease by implantation of low-activity 125I seeds in the tumor bed at the time of surgery. Six patients aged 2–14 years with recurrent tumors including two supratentorial primitive neuroectodermal tumors (n = 2), one medulloblastoma, one malignant ependymoma (n = 1), glioblastoma (n = 1) and one pleomorphic xanthoastrocytoma were implanted at the time of reoperation. A total of 11–126 seeds were implanted resulting in total doses of 16–21.8 Gy (after theoretical infinite time) at a depth of 5 mm from the implanted resection bed. Five patients had prior external beam radiation while the other patient (2 years old at initial diagnosis) progressed after surgery and chemotherapy. Two patients had lasting local tumor control. One patient is alive at 390 weeks of follow-up and another who died of distant failure at 366 weeks had no recurrence on MRI at 333 weeks’ follow-up. Only 2 patients had first local failures. These results suggest that the use of permanent low-activity 125I seeds as an adjunct to surgery can provide good local tumor control and is a suitable treatment option for pediatric patients.
Background:Patients with recurrent malignant gliomas have a uniformly poor prognosis. However, further treatment is often warranted at the time of recurrence. Low-activity implanted brachytherapeutic devices, such as iodine-125 seeds, and implantable chemotherapeutic devices such as 1, 3-bis (2-chloroethyl)-nitrosourea (BCNU) impregnated polymer wafers (Gliadel®) have been shown to be safe and modestly effective, but a comparison of combination therapy versus Gliadel® implantation alone has not been performed.Methods:We retrospectively examined 24 patients following re-resection of recurrent glioblastoma, with 17 patients undergoing implantation of both Gliadel® and iodine-125 seeds, and 7 patients undergoing implantation of Gliadel® only. Outcomes examined included adverse events, survival after re-resection (SAR), and time to tumor progression after re-resection (PAR).Results:Implantation of both Gliadel® and low activity iodine-125 seeds is safe with only two wound infections noted, a complication rate comparable to previous reports. The combination appears to confer a median SAR benefit if the activity per tumor resection volume exceeds 0.8 mCi/mL (60 versus 31 weeks, P = 0.02), and this benefit remained significant on multivariate analysis (HR =0.26 [CI:0.07-0.93], P = 0.03). Gross total resection of tumor was also significantly associated with longer time to PAR (HR =5.4 [CI: 1.13-26.0], P = 0.03).Conclusions:The concomitant use of Gliadel® and low activity iodine-125 seeds following re-resection of recurrent glioblastoma is safe. Our study demonstrated a significant benefit in SAR if the iodine-125 activity per tumor volume is greater than 0.8 mCi/mL. While our sample size is small, our results are in agreement with previous studies demonstrating the efficacy of combination treatment.
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