Local recurrence outcomes using the ³²P intraoperative brachytherapy plaque in the management of malignant lesions of the spine involving the dura

Purpose: Sterilization of surgical margins for lesions involving the dura is complicated by the tolerance of the spinal cord and/or cauda equina, especially in the setting of prior radiation therapy (RT); use of intraoperative brachytherapy may allow local delivery of therapeutic dose without damaging sensitive structures. Methods and Materials: Patients with malignant lesions involving the dura received intraoperative brachytherapy with a ³²P plaque after maximal resection of the tumor. Local recurrence (LR) was analyzed using competing risks analysis; overall survival was analyzed using Kaplan-Meier statistics. Results: Between September 2009 and April 2013, 68 patients with 69 lesions in the spine were treated with the ³²P plaque. Median followup was 10 months. Most patients (n=59, 85.5%) had previously been treated with at least one course of prior RT to the treated site. About 38 (55%) lesions received postoperative RT (median dose, 30Gy; range, 18-30Gy). The LR and overall survival at 12 months were 25.5% (95% confidence interval [CI]=15.5-37%) and 59.5% (95% CI=46-73%), respectively. For patients who received postoperative RT, LR at 12 months was 18.5% (95% CI=7.5-33%) compared with 34% (95% CI=18-51%) for those who were treated with the plaque alone (p=0.08 and 0.04 on univariate and multivariable analysis, respectively). There were no acute or long-term complications from treatment observed in this cohort. Conclusions: The ³²P intraoperative brachytherapy plaque is a useful adjunct to surgical intervention for primary recurrent and metastatic lesions of the spine involving the dura, and is not associated with additional toxicity.