A.J. Crimaldi

Effect of Polyether Ether Ketone on Therapeutic Radiation to the Spine: A Pilot Study.

Study Design. Cadaveric model. Objectives. To compare the effect of PEEK versus conventional implants on scatter radiation to a simulated tumor bed in the spine Summary of Background Data. Given the highly vasculature nature of the spine, it is the most common place for bony metastases. After surgical treatment of a spinal metastasis, adjuvant radiation therapy is typically administered. Radiation dosing is primarily limited by toxicity to the spinal cord. The scatter effect caused by metallic implants decreases the accuracy of dosing and can unintentionally increase the effective dose seen by the spinal cord. This represents a dose-limiting factor for therapeutic radiation postoperatively. Methods. A cadaveric thorax specimen was utilized as a metastatic tumor model with two separate three-level spine constructs (one upper thoracic and one lower thoracic). Each construct was examined independently. All four groups compared included identical posterior instrumentation. The anterior constructs consisted of either: an anterior polyether ether ketone (PEEK) cage, an anterior titanium cage, an anterior bone cement cage (polymethyl methacrylate), or a control group with posterior instrumentation alone. Each construct had six thermoluminescent detectors to measure the radiation dose. Results. The mean dose was similar across all constructs and locations. There was more variability in the upper thoracic spine irrespective of the construct type. The PEEK construct had a more uniform dose distribution with a standard deviation of 9.76. The standard deviation of the others constructs was 14.26 for the control group, 19.31 for the titanium cage, and 21.57 for the cement (polymethyl methacrylate) construct. Conclusion. The PEEK inter-body cage resulted in a significantly more uniform distribution of therapeutic radiation in the spine when compared with the other constructs. This may allow for the application of higher effective dosing to the tumor bed for spinal metastases without increasing spinal cord toxicity with either fractionated or hypofractionated radiotherapy. Level of Evidence: N/A

The effect of radiation therapy in the treatment of adult soft tissue sarcomas of the extremities: a long-term community-based cancer center experience

The aim of the study was to determine the effect of external beam radiotherapy (RT) in the treatment of extremity soft tissue sarcoma (STS) before or after limb‐sparing surgery (LSS) in a community‐based setting. Patients presenting to our institution from 1992 to 2010 and meeting eligibility criteria were stratified into low (G1) or high (G2, G3) pathologic grade and evaluated. Major complication events, including amputation, radiation‐induced sarcoma, and pathologic fracture, were assessed. Kaplan–Meier techniques and Cox proportional hazards regression models were used. One hundred and sixty‐two eligible patients underwent LSS for extremity STS (120 high grade, 42 low grade). Median time of follow‐up was 5.1 years (0.8–20.3 years). RT was administered to 111 patients. In unadjusted models, RT significantly decreased the risk of local recurrence (LR) in high‐grade STS patients (P = 0.005) and had a trend for improved recurrence‐free survival (RFS) (P = 0.069). In multivariable‐adjusted models, RT significantly improved time to LR (P = 0.001), RFS (P = 0.003), and overall survival (OS) (P = 0.003). Analysis of all patients showed those who underwent RT had a major complication rate (MCR) of 16.2%, compared to 3.9% in the no RT group (P = 0.037); however, the difference in MCR did not differ significantly when the analysis was restricted to high‐grade sarcomas. In our large experience of patients with extremity STS undergoing limb sparing surgery (LSS), RT significantly improved local recurrence (LR), RFS, and OS, in patients with high‐grade tumors. Efficacy benefits of RT should be weighed against potential complications. External beam RT should be considered in patients with resected high‐grade sarcomas.

ATNT-27ASSESSING THE SAFETY OF COMBINATION THERAPY WITH BEVACIZUMAB AND OPTUNETM FOR HIGH GRADE GLIOMAS.

BACKGROUND: The prognosis for patients with high grade gliomas remains dismal. In addition to cytotoxic therapy, the FDA has approved bevacizumab and OptuneTM (Tumor Treating Fields) for recurrent glioblastoma. Given the prognosis and multiple treatment options, many clinicians have elected to offer combined therapy. We examined our patient population at two institutions where combination therapy has been used. METHODS: We retrospectively reviewed clinical courses of all patients receiving OptuneTM who have been concurrently managed with bevacizumab or experienced prior therapy with bevacizumab. Toxicity was described for those patients. Patients who received OptuneTM for at least 4 weeks with concurrent bevacizumab were analyzed for overall survival from time of initiation of concurrent therapy. RESULTS: We identified 37 patients, 26 males and 11 females. Of those, 33 patients received concurrent therapy, and all of those patients had prior bevacizumab exposure. OptuneTM was started as single therapy in 4 patients after bevacizumab exposure and failure. 6 patients experienced contact dermatitis which did not delay therapy. 1 patient had a small skin erosion which did not delay therapy. 2 patients had small skin erosions which delayed OptuneTM therapy. 1 patient had folliculitis and skin erosions and ulcers which necessitated cessation of therapy. 1 patient had a grade 2 intracranial bleed with no clinical sequelae aside from the need to hold bevacizumab. 29 patients received this therapy for at least 4 weeks. Median duration of concurrent therapy was 4 months. Median OS from initiation of concurrent therapy was 5.3 months. CONCLUSIONS: In our dataset, there was no toxicity appreciated aside from mild skin toxicity in the majority of patients. Combining bevacizumab and OptuneTM does not appear to significantly increase risk of bleeding or stroke. The incidence and severity of skin reactions were comparable to those described previously. Additional trials to investigate this combination are ongoing.